When you do productive labor (like at a job), you are able to use what you produce (or some negotiated amount of payment related to what you produce). How you use your income can be broadly viewed in two ways: investment and consumption.
Investment fundamentally means capital accumulation – putting your income towards the accumulation of capital goods which raise the productivity of labor and thereby create a progressing economy which offers exponentially (like compound interest) more and more production each year. The alternative is to consume your income – spend it on consumer's goods like food, video games, lipstick, cars, etc.
People do a mix of savings/investment and consumption. the proportion of the mix determines how good the future is. A high rate of capital accumulation quickly leads to a much richer world which is able to support far more consumption than before while still maintaining a high rate of investment (the pie gets larger. Instead of consuming 80% of the original pie, one could soon be consuming 20% of a much larger pie which is also growing much faster, and that 20% of the larger pie will be more than 80% of the smaller pie.)
For more info on the economics of this, see the diagrams on pages 624 and 625 of George Reisman's book Capitalism: A Treatise on Economics and read some of the surrounding text.
The situation with your intellectual labor parallels the situation with laboring at a job for an income. Your intellectual labor is productive and this production can be directed in different ways – towards consumption, towards increasing the productivity of intellectual labor, or a mix. The more the mix favors increasing the productivity of your intellectual labor, the brighter your future.
Consumption in this case refers to things where you aren't investing in yourself and your education – where you aren't learning more and otherwise becoming more able to produce more in the future. For example, you might put a great deal of effort into writing a book which you hope will impress people, which you are just barely capable of writing. It takes a ton of intellectual labor while being only a little bit educational for you. Most of your intellectual labor is consumed and the result is the book. If you had foregone the book in the short term and invested more in increasing your productivity of intellectual labor, you could have written it at a later date while consuming a much smaller proportion of your intellectual output. This is because you'd be outputting more and even more so because your output would be more efficient – you'd be able to get more done per hour of intellectual labor (one of the biggest factors here would be making fewer mistakes, so you'd spend less labor redoing things). A good question to ask is whether you produced an intellectual work in order to practice or if instead you put a lot of work into polishing it so other people would like it more (that polishing is an inefficient way to learn). It's sad when people who don't know much put tons of effort into polishing what little they do know instead of learning more – and this is my description of pretty much everyone. (If you think you already know so much that you're largely done with further educating yourself, or at least ready to make education secondary, please contact me. I expect to be able to point out that you're mistaken, especially if you're under 50 years old.)
Consumption (rather than investment), in the realm of intellectual labor, primarily relates to going out of your way to try to accomplish things, to do things – like persuading people or creating finished works. It is possible to learn by doing, but it's also possible not to learn much by doing. If you're doing for the sake of learning, great. If you're doing for the sake of an accomplishment, that is expensive, especially if you're young, and you may be dramatically underestimating the expense while also fooling yourself about how educational it is (because you do learn something, but much less than you could have learned if you instead studied e.g. George Reisman's Program of Self-Education in the Economic Theory and Political Philosophy of Capitalism or my Fallible Ideas recommended reading list.)
Broadly, I see many people try to produce important intellectual works when they don't know much. They spend a lot of intellectual labor and produce material which is bad. They would have been far better served by learning more now, and producing more output (like essays) later on when they are able to make valuable intellectual products with a considerably lesser effort. This explains the theme I've stated elsewhere and put in the title of this piece: you should intellectually do (consume) when it's relatively easy and cheap, but be very wary of expensive intellectual projects which take tons of resources away from making intellectual progress.
Some people doubt the possibility of an accumulation of intellectual capital or its equivalent. They don't think they can increase the productivity of their intellectual labor substantially. These same people, by and large, haven't learned speed reading (or speed watching or speed listening). Nor have they fully learned the ideas of great intellectuals like Ayn Rand and Ludwig von Mises. Equipped with these great ideas, they'd avoid going down intellectual dead ends, and otherwise create high quality outputs from their intellectual labor. Even if the process of increasing the productivity of one's intellectual labor runs into limits which result in diminishing returns at some point, that is no excuse for stopping such educational self-investment long before reaching any such limits.
In the long run, the ongoing increase in the productivity of one's intellectual labor requires the ongoing creation of new and improved intellectual tools and methods, and supporting technologies. It requires ongoing philosophical progress. I believe philosophical progress can be unbounded if we work at it (without diminishing returns), but regardless of the far future there is massive scope for productive educational self-investment today. Unless you've exhausted what's already known about philosophy – that is, you are at the forefront of the field – and also spent some time unsuccessfully attempting to pioneer new philosophy ... then you have no excuse to stop investing in increasing the productivity of your intellectual labor (primarily with better and better methods of thinking – philosophy – but also with other things like learning to read faster). Further, until you know what is already known about philosophy, you are in no position to judge the far future of philosophical progress and its potential or lack of potential.
Note: the biggest determinants of the productivity of your intellectual labor are your rate of errors and your ability to find and correct errors. Doing activities where your error rate is below your error correction capacity is much more efficient and successful. You can increase your error correction effectiveness by devoting an unusually large amount of resources to it, but there are diminishing returns on that, so it's typically an inefficient (resource expensive) shortcut to doing a slightly more difficulty project slightly sooner.
The article is itself an example of what I can write in a few minutes without editing or difficulty. It's the fruits of my previous investment in better writing ability in order to increase the productivity of my intellectual labor. I aim primarily to get better at writing this way (cheaply and efficiently), rather than wishing to put massive polishing effort into a few works.
What I say in this post is, to some extent, well known common sense. People get an education first and do stuff like a career second. Maybe they aren't life-long learners, but they have the general idea right (learn how to think/do/problem-solve/etc first, do stuff second after you're able to do it well and efficiently).
What goes wrong then? Parenting and schooling offer a bad, ineffective education. This discourages further education (the painfulness and uselessness of their education is the biggest thing preventing life-long learners). And it routinely puts people in a bad situation: trying to do things which they have been educated to be able to do well, but in fact cannot do well. The solution is not to give up on education, but to figure out how to pursue education effectively. A reasonable place to start would be the books of humanity's best thinkers since the start of western civilization. Some people have been intellectually successful and effective (as you can see from the existence of iPhones); you could look into what they did, how they thought, etc.
FI involves ideas that are actually good and effective, as against rivals offering similar overall stuff (rational ideas) but which are incorrect. FI faces the following major challenges: 1) people are so badly educated they screw up when trying to learn FI ideas 2) people are so badly educated they don't know how to evaluate if FI is working, how it compares to rivals, the state of debate between FI ideas and alternative ideas, etc.