No question about it, the minor leagues are tough. Those that have been to college first have a big advantage in many ways.
However, if the contract is good enough it's a lot easier to deal with minor league baseball. And if we think it's so bad on young high school players, think about how hard it is for Latin kids.
The odds of making it to the top are long, but definitely far from impossible. Somebody has to play in the Major Leagues. Many have signed out of high school and made it big. As far as getting easy... I'm not sure that ever happens.
One other thing... If minor league baseball was so difficult to deal with, MLB clubs wouldn't have to release players so much. Most of them would be quitting and moving on. Very few players want to give it up quickly. Most are very happy to keep the dream alive and play baseball in front of lots of fans nearly every night. That's nothing to complain about, it is exactly what most young players want more than anything, yet only a small group gets that opportunity.
My suggestion is to those who don't love it... Don't do it! Coming out of college or high school won't matter. It will be too difficult, you probably won't like it.
I do think this is a great topic. It's good that people understand what pro baseball is like. The older I get, the more appealling going to college first seems to be. Going pro for a little bit of money doesn't make much sense. Especially when so many players develop so much (in many ways) during their college years. The college kids are more prepared for whatever happens.