I'd take the 3 mil I'd have left after taxes, and invest 2 mil of it with an extremely diverse portfolio, probably 40% in steady growth, low risk stocks, 40% in mutual funds and 20% in higher risk stocks.
I'd complete the rest of my contract with uncle Sam, then never work again. After I'm done with my contract I would invest in restaurant franchises. I'd oversee the construction, but once they were up and running they wouldn't see me much. While I'm still in I would invest in houses that I could get a deal on, then have a property management company take over and sit back and let the rent money flow in.
I'd buy a house for myself that's more garage than house, because I'd have quite a few cars and a massive home gym with a monolift and tons of other goodies.
After all my businesses are up and running by themselves, I'd get a sick RV and travel. Mostly in the mountains. By the time I died I would have turned that 3 mil into 7+, and my family would bet set.
Current PRs at 242- 495, 345, 585, 1425