Drugs are cheap. Patent monopolies are expensive. These are simple facts that everyone should know, but for some reason few do.
The point here is simple; the vast majority of drugs are cheap to produce. Chain drug stores sell hundreds of generic drugs for $5-$7 per prescription. They can do this profitably because few drugs require expensive chemicals or manufacturing processes.
However, many brand drugs sell for hundreds or even thousands of dollars per prescription. This is due to the fact that drug companies have patent monopolies on these drugs. The government will arrest anyone who produces these drugs without the permission of the patent holder. Since drugs can be essential for people's health and/or life, if they can find a way to pay any price demanded by the drug companies, they will.
The higher prices due to patent monopolies are the reason that many people have difficulty paying for drugs. If all drugs were sold in a free market as generics, paying for drugs would not be a serious issue except for the very poor.
Of course, patent protection is the way in which drug companies finance their research. It costs a lot of money to research new drugs and then test them to establish their safety and effectiveness and bring them through the Food and Drug Administration's approval process.