The guy that drives the sewer sucker truck, and vacuums the poop from outhouses makes a lot of money too. Like the porn star, his pay is commensurate with the nature of the job he is performing.
I'm speculating, but I bet that porn stars don't enjoy sex, and that is the price for the job they perform. If your day consists of being paid for having sex, it's probably difficult to have a real relationship and actualy enjoy having sex. Your parts are going to be sore from overuse and your interest is going to be lacking.
Also, porn stars don't make as much as the video suggests. The market is flooded with porn, most of it free internet porn, and as a result, the entire industry is in a massive recession. Budgets have been slashed and porn stars are trading their Mercedes in for Hondas.
It's better to use your brain to make money. But if your ass is all you've got going for you, then by all means, maximize the money you make from exploiting your bung, as it will dry up, pardon the pun, eventually.