I'd be interested to know the number or ratio of startup created by under 30 and have failed vs number of startups created by over 30 and failed. My guess is there'd be less failure by over 30 founders.
Most research points to mid/late 30's as the peak of technological breakthroughs (largely determined by age of Nobel winning work). I'd actually be somewhat surprised if successful company founders weren't largely distributed around that same range.