First of all a mind running at 1000x the speed is quite different from a person living to 75000. Imagine boxing (with gloves and all) with somebody while you could move at twice the speed - this is quite different from boxing with somebody while you have twice his stamina (in the latter case you will win after a long and equal fight where your opponent gets tired. In the former case I'd be surprised if your opponent managed to land a hit).

Secondly: If I have 75000 years to waste I might as well take over the world at some point. Seems like a good return on investment. And really, how hard can it be? Maybe 300 years, tops?