As to wealth accumulation he could have gained and lost fortunes many times over before accumulating it again.
Surely this is the case. Otherwise, I'm imagining an earlier Flint, once again moving on before his nature is suspected, traveling in a freight train, loaded to capacity with his accumulated wealth in tow. No way he wouldn't draw attention to himself sooner or later...an obscenely wealthy drifter?
He probably could have ruled the world at some point if he chose. Interesting, how he elected "life" after "life" to exist in almost complete anonymity. His Brahms and Davinci periods were probably among his most hated and feared, in a way. The greater the fame, the greater the watchful gaze of the curious, the meddlers, the fools. I seem to remember someone mentioning those things...
I like the 'smaller size' of know space and space exploration implied by Flint having purchased the planet "only" 30 years earlier. You'd think he would have done it sooner if he could. So, while Kirk wasn't quite old enough yet to dip little girls' curls in inkwells, Flint was only then able to make his big move to another world.