Q, as usual, is spot-on for non trad financial advice.
OP, forget the ROI calculators and spreadsheets. There are a dozen in the non-trad forum, and they all say the same thing. I can save you a ton of work and just give you the answer here.
If you matriculate medical school at age 40, you will die with just as much money as if you didn't go to medical school. If you enter med school before age 40, you come out ahead. If you enter after age 40, you are at a financial loss (but at age 40 you realize there are more important things in life than just dying with the most money). It never seems to matter how you set these calculations up, they always spit out the same answer. Start med school after age 40 like I did and it's a labor of love.
Also, please note that federal student loans are forgiven if you become disabled. But it is a taxable forgiveness so you will suddenly owe taxes on hundreds of thousands of dollars of phantom income. When you are disabled!!! This isn't theory, it's a big problem and it has been happening for years now. Plan ahead!
http://mobile.nytimes.com/2014/03/2...de-loan-debt-for-a-tax-bill-from-the-irs.html