Why aren’t esports as profitable as mainstream sports like football and basketball?

Mostly because they give all their content away for free.

Most critically, leagues like the N.B.A. and N.F.L. earn billions of dollars each year through broadcast deals with television networks, while many e-sports are streamed for free on sites like YouTube and Twitch. Some early revenue projections included anticipated broadcasting deals with Twitch and YouTube that were less lucrative and consistent than expected.