You are wrong, centralized exchanges do not ruin bitcoin decentralization.
Centralized exchange mostly ask you to use your real name and real information during sign up, if you're submit fake information and they ask your KYC, you will in trouble. Centralized exchange do record your IP address, you're not allowed to use VPN.
This mean even you're not submit your KYC, the centralized exchange already know some of your information and they will record it.
I don't think private information in centralized exchange is secure due to hack and data breach, privacy is one of few important thing in decentralization.
People that store their coins on exchanges is doing that because of ignorance. It is stupidity to people that know how stupid it is to store coins on exchanges.
I'm not talking about the security of centralized exchange, but I tell the fact. If all people are store their coins on their non custodial wallet, the hacker who hack the exchange will not able to steal huge amount money because people move their coins on their own wallet, right?
Bitcoin do not need Twitter, the adoption will continue because people have many other social places they can be exposed to bitcoin. Without Twitter, bitcoin adoption will continue. Can you even tell us a way that Twitter or Elon Musk gas helped?
True Bitcoin do not need twitter, but if twitter adopted Bitcoin, there's always an effect regardless it's small or big.
Twitter or Elon Musk not really help a lot since they only accept Bitcoin, that's all. But most people taking it as serious just like they reacted to twitter logo replaced with Doge.