Comment by AlanYx

This is really the critical thing: the fun is the incentive. (Or at least the dominant incentive in math, historically.) As economists like to say, the overarching lesson in economics is that incentives matter. Reduce the incentives and participation will decrease.

Perhaps that won't matter if we enter an era where AI participants are the main participants who matter for discovery-level mathematics. But it would likely be what economists would see as a market failure if only a small oligopoly of AI participants, closely held behind closed doors, is able to fill that intellectual role.