A:
I travel with my ChromeCast so that I can watch the programming that I want, anywhere in the world. For example, I broadcast from my tablet to watch Netflix in my hotel room in Norway.
At home, I do not have a device with built-in application software (Netflix, Hulu, &c.) so Chromecast fills a void for me that may not be as big for you.
Alternatively, my daughter uses Chromecast at college & has no need for a DVD player, TiVo, Firestick, &c. - only Chromecast & her phone or laptop.