There are many reasons why someone might want to run their own miner:
I found this guide right here https://www.econoalchemist.com/post/home-mining-for-non-kyc-bitcoin
The focus he makes is for non-KYC but the guide is very good. The main takeaway from this is that the myth of home mining not being profitable is absolutely false. Sure, home electricity is not cheap, and sure, the miner will need some proper installation for heat and noise. But it is doable. And for a bitcoiner, even with a pitiful single miner, decentralization matters.
As for the ROI, if you’re thinking long term and don’t plan to sell those earned sats, they will more than make up for the initial investment (which is sizeable.)
The miners themselves have a reputation of being built like tanks. You might have a fried circuit here and there but in general people say they last long. So an investment of about 2000 euro in a miner will hopefully last for years.
The way I see it, the only real problem with this entire DIY project is buying the miner itself. They are always sold out from the company and there are hundreds of legit-looking scams out there. Frankly, it’s the only thing that would deter me from buying one, since it is a sizeable amount of money.
There’s a video from a different person for the Antminer S9 setup here: