many reasons we can assume why they hate bitcoin, such as
business failure caused by losing competition with bitcoin
- exposed to a scam on a site or investment place in the name of bitcoin
- stolen bitcoin
- or most often there are losses from trying to invest in bitcoin
- etc
however, there is a reason why they hate bitcoin. maybe it was the reason that changed their life. however, it's best to ignore them, and try to focus and make use of bitcoin, or altcoins. when you make a profit with it, when you have bought real estate, or when you are successful in this path, they can only denounce it.
In addition, remember one thing, that no matter how good the technology is, there will definitely be people who hate it.