Medical School To Practice Medicine

I never understood it. You apply to medical school theoretically of course to practice medicine. You apply to schools including some you never think you would get into, some you would like to theoretically go to, and some that are lower, but if they are the only ones you get into, well you go there, because the end result is hopefully the same, you are a doctor. And just incase you didn’t know, there are 2 types of medical schools. There are MD schools of course and then there are DO schools. MD schools are the ones we all know. DO schools were previously looked down upon and a second choice, but not nearly as stigmatized now.
A friend of mine applied to medical schools and a few DO schools as is customary. He is now applying for his third year, third time, and before I was under the impression that he hadn’t gotten into any. Acceptance to medical school can be rather arbitrary. It depends on what they’re looking for. They could be looking for the right things to say, the right experiences, the right grades, the right MCAT score, the right something, it always depends. I know a guy who actually got into a rather prestigious medical school that anyone would love to go to, but ironically didn’t get in anywhere else! How does that happen?
But as it turned out, he previously was accepted into a DO school, he went to the interview, because generally speaking you have to go to an interview once they decide they like you and then you get accepted or not accepted after that. They don’t come to you. If you live in a different state or area, you go to them. So basically he spent the money on the applications, he spent the money getting out there for an interview, and then he decided that he had applied there, gotten in only there, and he was too good to go there? What was the point of even applying in the first place!