Investments need a return on investment. If "the thing you wanted to exist now does" is the only return, that's not enough to support anywhere near the current amount of digital product creation happening today.
Given that people are already accustomed to paying for the promise of future things existing in the form of crowdfunding, Patreon or most subscription services in general, I don't think it would as drastic of a difference as you imagine, as long as the infrastructure is there to facilitate effortless 'investing' into many small things.