Some people will go through the verification steps as soon as they create an account on an exchange, I think it's a habit.
Any centralized exchange can lock your account and demand KYC at any time. If you don't care about completing KYC, then you might as well just do it to prevent your account being locked in the future.
Data breach can happen anywhere in this world online or offline it doesn't matter so living this life is already a risk
Every time you get in a car you take a risk. Doesn't mean you should drive with your eyes closed.
and if data breach happens I don't care
You won't be saying that when your identity is stolen and you end up on the hook for $50,000 in debt and credit cards you didn't open. You won't be saying that when someone links your identity to being an active bitcoin trader and shows up at your house to steal your bitcoin. KYC is
always a risk.
but a proper exchange or any service for that matter should be storing this kind of information off the server, rather than live.
We know that that doesn't happen though. Not only do they store your information online, but they send it over the internet to third parties for verification, processing, storage, etc. You have absolutely no idea where your information ends up and who has access to it after you complete KYC.
you can only escape KYC verification if you don't need Fiat
Not correct. I have never completed KYC and I trade between fiat and bitcoin regularly via peer to peer trades on platforms like Bisq.