Tangential, but even movies and music are smaller than the games industry.

The entire, global music industry, for 2016, was worth $16 Billion. The global movie box office total for 2016 was just over $38.6 Billion US dollars. [...] Meanwhile PC games alone earned $34 Billion (including sales, DLC, subscriptions and in-game transactions). Console games pulled in $30 Billion (including hardware, games and services). and Mobile games topped $40 Billion (sales and in-game transactions).

https://www.quora.com/Is-the-Video-Game-industry-bigger-than... (Which isn't sourced, but the numbers seem consistent with this https://www.vanillaplus.com/2018/07/05/40093-video-games-mar...)

I don't know what the numbers are for ebooks; this link says 1 billion US dollars revenue in the US market.