I think I would because I know what it's like to have a real job and pay my bills with it - as opposed to being born into a rich family or striking it rich because you were the right tech bro at the right time and you got lucky (and you fucked your partners over a little too).
There's a million interesting social projects I would like to donate to. People and organization who don't need all that much to do a ton of good around them. I would feel truly happy to donate to them and feel as though I had a net positive impact in my community.
And also, I despise the arrogant tax-evading billionnaire class so much, I don't think I could live with myself if I realized I had become one of them without realizing some day. Just that thought alone would keep me on my toes every day I think.