If the OP is planning to spend "a few years" travelling in Europe without working then 140,000 US dollars isn't going to last very long, not even with the parental top-up... so I doubt he'll be seen as someone who is going to spend "a lot of" money, and I doubt embassies will be falling over themselves to give him a visa.

As has already been pointed out overstaying one's welcome is never a good idea... and neither is trying to bribe government officials into issuing visas that they are not supposed to issue.

So, really, it's likely that the only options are (a) to spend 90 days out of every 180 outside Schengen (i.e., in the UK, Ireland or any of a number of countries in Eastern Europe), or (b) to go through his family tree and see if he might be able to apply for citizenship of a European country based on the citizenship of recent ancestors.