I do it for convenience. I have fast internet, but battery consumption of tabs and mobile is too high for my comfort with data/wifi turned on. I download 4k/2

I do it for convenience. I have fast internet, but battery consumption of tabs and mobile is too high for my comfort with data/wifi turned on. I download 4k/2k videos for anything super interesting and >= 30 minutes and watch them later. Some episodes of some podcasts are super worth it to keep in your hard disk. I also download and save Chopin and Bach playlist to device and then later play them for long hours. Videos disappear a lot on YT. Interesting videos that I saved on "Watch Later" disappeared quite a few times.