How much can I reasonably expect to make via stable, passive income, off of $15MM?

I'm running my own business and I don't want to reach the selling point in a few years and then realize that selling a business and netting $15MM isn't all it's cracked to be. I want to be able to retire early and have more than enough money flowing in to fund a $600k/year lifestyle.

If this is possible, what vehicles/instruments would I need to invest in? Is this even realistic?

Again, I don't want to be working my butt off in order to get a prize that doesn't even exist...