2002… uff, that would be hard. As a ten year old there is so little you can do!
I guess I would steal an identity and get some ground breaking research out on a quicker time scale. In particular trying to get ahead of the climate deniers. I would invest in some whatevers that made it big as soon as possible, then during the 2008 crisis, then Bitcoins.
I would find it impossible to not look for my friends and family, even just stalking them from afar. That would probably drive me insane.
I’d use my wealth to lobby hard for climate justice and climate research. Probably still hide my true identity. I’m not American, so I would need to think really hard if preventing Trump is worth it, but I would lobby for a quicker energy transition and for a better social net. I’d assume with the knowledge I have at hand, I could even tweak the end result of the 2008 crisis… but that would be a massive butterfly to introduce.
On a global scale, I would think that some properly timed interventions in Africa could have dramatic impacts both socially and ecologically, but I’d have to study more to figure that out.