I'm going to assume I'm 18 so I can do whatever I want! (It's only 3 years away, anyway
I'd start up my own charity, which would work for combating a bunch of problems. Changetherules.org has some really amazing principles - they explain exactly WHY there is so much poverty/inequality in the world and are trying to get the international economic rules changed to help fix it. THAT'S what I call getting to the root of the problem! We'd also work on the global footprint problem - finding more reliable, reasonable (not too expensive, works well) sustainable energy sources and put them into practice. So throw away about $500 000 there
. Then I'd build some schools for children in poor countries. I'd have to build a lot, and probably train a fair few teachers for it as well. So that would be at least another $100 000.
Then I want to put about $250 000 into cancer/disease research.
Then I want to put about $50 000 into starting a political party which has a bunch of policies that I like. I would be head of that, of course.
Now I have $200 000 left for myself. I'd invest $100 000 of it (I'll have to work out how to do that) and get more money out of it to put into my political party and charity funding (and to live off.)
The other $100 000 would be put into funds to a) take my family on a massive, six-month holiday around the world ($50 000, b) some so I can send my kids to a great private school (this would not cover all of the costs but it would help) ($40 000), and c)some to spare in case I need it ($10 000).