This reflects a belief in Bitcoin's potential as a store of value and a hedge against inflation. Long-term holders and institutional investors, in particular, may be taking a more strategic approach to their Bitcoin holdings, viewing them as a strategic asset allocation rather than a short-term speculative investment.
I just responded on a similar type of topic where the OP showed the same concerns, basically I just to think about another cause of this outflow is Binance fuds, as we all know when Binance was sued and blocked by Binance, and now Nigeria, people started to withdraw there funds from CEXs, I also withdrew my funds from Binance when I come to find that my country has also asked Binance to pay the Fine
I knew why would Binance pay fine to our country, so I suspected things might go wrong side so I withdrew all of my funds, and many other fellow might have suspected the same. This fud has created a stress among the investors, and besides this market is now in bullish state, and many hacked has been occurred also, plus people are more educated too, so they prefer to use non-custodial wallets. One thing I know suspect is people might not prefer non-custodial wallets especially for the BTC coin, due to the high fee on transaction.