No, it doesn't sound good. I'd say (as I've said about ten times already) that you're far too young to be trying to figure out your educational career for the next two decades. You don't even know what the degrees are, much less whether or not you can or will obtain them. Chill out. You've got three years of high school left, so concentrate on them.
And no, you generally cannot obtain a master's degree in one field and then obtain a Ph.D. in another, unless the fields are exceptionally closely related. You're not going to be able to go from medicine to astrophysics, no matter how smart you are -- it just isn't possible. You seem to be drastically underestimating the amount of education that goes into being a practicing doctor, or a professional astrophysicst. Each of those careers require something like 10 years of highly specialized education. If you want both degrees, you will probably need to spend twenty or more years in a university, not making a dime. Since you seem so highly motivated by money, it doesn't sound reasonable at all.
You should also realize that in the physical sciences, a master's degree is often given as a "consolation prize." In other words, everyone attempts to obtain a Ph.D., and if you fail for some reason, you're kicked out and given a master's. If you decide to pursue astrophysics, you will need to pursue it whole-heartedly, starting in the later years of your undergraduate degree.
You will almost assuredly have to abandon these wacky ideas about obtaining multiple degrees in totally disparate fields. It isn't a menu -- you don't just go to a university and order a master's in one thing, an MD, and then top it off with a Ph.D. in astrophysics.
- Warren