I think the market & political/economic actors as a whole are justifying these investments on the basis that the benefit is distributed across the labour market generally.
That is, it doesn't matter so much if OpenAI and individual investors get fleeced, if there's a 20-50% labour cost reduction generally for capitalism as a whole (especially cost reduction in our own tech professions, which have been very well paid for a generation) -- Institutional investors and political actors will benefit regardless, by increasing the productivity or rate of exploitation of intellectual / information workers.
That is, it doesn't matter so much if OpenAI and individual investors get fleeced, if there's a 20-50% labour cost reduction generally for capitalism as a whole (especially cost reduction in our own tech professions, which have been very well paid for a generation) -- Institutional investors and political actors will benefit regardless, by increasing the productivity or rate of exploitation of intellectual / information workers.