Following the recent Bitcoin ATHs, C0inbase subredditors are now gaslighting people that storing your coins on that exchange is more secure than self-custodying.
You said Coinbase subredditors
Coinbase is an exchange and there are some people there that may just like to mislead people.
I am not active on Reddit but the best forum I know that I can see the true information about what bitcoin and exchanges are is still on this forum, Bitcointalk.
You saw what Binance CZ posted about this when people were moving coins from Binance to a noncustodial wallet. Those that are working for an exchange may just like to mislead people.