It takes more effort to repair a badly laid road than to lay one out for the first time. One needs to dig out all the tar before leveling and laying down a fresh layer.
It takes more effort to repaint a house than to paint it for the first time. One needs to scrape out the layers of old paint with sandpaper before laying down new coats.
It takes way more effort to unlearn something and course correct than to learn it right the first time around. All those neural pathways in the brain need to be undone and rewired in a manner similar to excavating bad roads or scraping old paint off walls.
The value a teacher or a trainer brings is to lay things down correctly the first time around. This value cannot be understated – more so in a world of online education and do-it-yourself learning.