First of all, I think for me, the best way to make a decision is to work as an RN first, get exposed to these advanced careers, then decide which one I like most and want to proceed.
But monetary wise, I would think although MDAs make more money, residency is pretty competitive. And before that, one need to work very hard to get into medical school first. That is a very tough process itself. From my perspective it requires much more time and committment than preparing for BSN school, or even CRNA school.
To get into CRNA school, you work in acute care field. But you are doing your job and making not bad money compared to other professionals. If you do not plan to go to CRNA school, you still do the same job and make the same money. You are not losing anything preparing to go to CRNA school. But to get into medical school, most schools require voluntary experience, and to be competitive, one might need more time, basically you work for free. This need to be included into MDAs cost. (giving our topic, I am not including the benefits of helping other people, different exposure, life experience etc, from voluntary experience, which, are of course, very important and cherishable)
Also, from RN-BSN, most likely I guess one can get some financial assistance from the hospital. But with pre-med, who is going to pay tuition for you? and to maximize your chance, you need to go to a good school, and face a tough competition: everybody in pre-med program wants to maximize their GPAs. But in RN-BSN program, how many of them have decided they want to go for CRNA? On equal-credit basis, you need more time on pre-med program than on a BSN program, which means, you are making less money during pre-med than during nursing school becuase you are spending more time studying.
What if one cannot get into a US medical school? OK, he goes to a carribean school, now probably will end up with a internal medicine/family practice physician, basically earning the same money as CRNAs, this also applies to a common US medical school graduate. Same with DO schools.