Seems like a slight false dichotomy. Founders can work on on frivolous businesses initially, but later on, once they've acquired the acumen and resilience to be a proper CEO, they may turn their hands to grander projects. Incubators like YCombinator are training legions of entrepreneurs to be better entrepreneurs (as a side effect of finding successful exits occasionally).

Two other thoughts: shouldn't we be looking at big, wealthy companies to do the major, game-changing R&D anyway?

And secondly, maybe the world has changed in such a way as to allow big breakthroughs to be dominated by mega corporations.