The problem is all these businesses (ride share, food delivery), have extremely low margins and the tech to spin up a competitor is extremely cheap and commodity.
Thus the “monopoly” you allegedly get later is deeply unsustainable at the profit level and scale required to recoup losses on any timescale that would work for investors, assuming you can even hold onto it in the face of constant reemergence of competitors.
This is what Naked Capitalism has been point out about Uber for years and years. Uber just keeps changing the story. First rideshare itself would be profitable. Then logistics and trucking would be a sexy new profitable area. Then self-driving cars, then food delivery.
It’s frankly just a Ponzi scheme at this point that was foisted onto unwitting retirement plan investors.
GrubHub / DoorDash / etc., are just more of the same.
You can’t take businesses like taxis or food delivery, with well understood economics, round trip costs, density requirements, low margins, etc., and just slap an app on top and make them somehow different than they really are.
Artificially increasing the supply of something that’s fundamentally not sustainable at that price just will not work.