See the future.

I don't particularly see myself as wise enough to have the power to affect the world to such an extent that changing the past would have. There's no way for me to know how much I may end up changing after so many years, and things could end up much worse than they were before. Maybe not for me but for other people who don't deserve it. I could never be truly sure, I'm not omniscient. However, knowing the future is only going to affect my life and the rest of the world from that point on according to how I use that knowledge (and I don't necessarily even have to, really), ergo I have more control over the situation.

Hm, that's a good question.

But I would rather see the future, that way I can avoid bad decisions.

See into the future, so I can trick people into believing I'm some madman from the future.

Or I could win the lottery...