1. The audience changed. Billions of people came online in the 2010s on smartphones, streaming works better for them.

2. For most people bandwidth did not increase at the same rate as video file sizes during that period, streaming could do smart things like serve transcoded media sized to fit your screen and internet connection. It's only recently with HEVC and AV1 that video file sizes have caught up.

3. Streaming can be easily monetized, p2p generally cannot.

Yes, because the amount of pirated content floating around was not 1/100th the amount that is out there now, and obtaining content is easier than ever. Especially when you have a sanctioned "library" that hosts it all for you for free.