Honey, costs are measured in things besides dollars, and there are fields outside of medicine. You don't just give up the cost of attendance, you also give up any income you might have made outside of medicine.
There is no question that my income will likely surpass that of my friends outside of medicine some day, but I am unlikely to make more total money than they have until well into my 40s. It's not that my friends are super rich, it's that they have almost no living costs and are making 50-80k.
By going into medicine, you give up your income for seven years. At the moderate end of the spectrum (among my friends from high-school and college), that's 50k/year. That's $350,000. In addition, I am going 200,000 dollars further into debt. The interest increases that to around 300-400k, depending on the speed at which I pay it off. So, my friends start at a 750,000 dollar advantage.
What's more (even if we assume they make no more money in seven years than they do now), they can invest that money. Money invested will grow. Overall, the amount of money my friends outside medicine will make is probably still greater than $750,000.
While we're still exploring the idea of opportunity cost, I should point out that most of my friends work 50-55 hours on a "bad week," and the rest of the time is "free." For me, at least, these are probably some of the healthiest years of my life. The point is, the cost isn't just in money, which is substantial. It's also in time.
Fortunately for me, I really enjoy what I'm doing. I can't imagine doing anything else.
However, I think medicine would have been a poor life choice if I didn't.