Thank you for pointing out one of the big upsides to entrepreneurial bubbles. (Not necessarily all "speculative" bubbles.)
The simplified form is that a "gold-rush" mentality in an entrepreneurial bubble, even though it misprices risk generally, incentivizes builders to go build things more than they would, and since on balance building things is good, a hyper period of new venture formation still leads to net gains even if most are failures.
But nostrademons has a next-level mechanic here -- the idea that stage and scale are not fractal, and hence that rebuilding an ecosystem de novo (perhaps in a sort of sheltered petri dish) can yield big interesting beneficial outcomes because of the plasticity of things at the smaller scale and earlier stage.
(Still, I think it's a monumentally bad idea to acquiesce in the rebuilding of the financial system de novo by amateurs.)