why do homelab enthusiasts want to set up their own cluster ?

I got to know a few IT personnels and all of them have some form of homelab at home . They will buy lots of computers (ranging from rasberrypi to used laptops to full fledge servers) to build a cluster of servers at home . not 1, but a cluster of servers.... I dont see a practical need for these?

They use it to store data of temperature, humidity, PM10 of their homes, and host their own websites. home automation, maybe their own games, videos... so that they can watch video while on a tablet in their toilet.

i can understand the need to have home media server or server for home automation, but most of them live alone. plus, there is such a thing called external drives you know. you dont need a cluster of servers for one person use, a single server is sufficient and its not like they run their own business, plus business these days use cloud or shared hosting.

there is no reason why would you want to stream video or games on a tiny tablet , if you are rich enough for a home lab, you are rich enough to get a home theatre.

The only legit reason i know of is someone i know hosting their porn on it (and its port forwarded to the internet). they cant host it on someone else server because no one is willing to.

Other than that i dont see why do you need a cluster of servers for home use. Its completely overkill.