Holding our coins in non-custodian wallets is still the same thing as staking if we maintain the discipline of not touching it the only difference is that apart form the increase in the value there is no extra reward in terms of quantity in the amount of holdings.
Holding bitcoin in a self-custodial wallet is different from staking bitcoin on a centralized exchange. Before you can stake bitcoin on a centralized exchange, you need to move your bitcoin to the centralized exchange where you want to stake it, which will give the centralized exchange access to your bitcoin, and your bitcoin will be at risk because you don't have access to the private key. The centralized exchange team can cook up a cock and bull story that their exchange was hacked and they lost all their assets to the hackers just for them to steal your bitcoin without you suspecting them. Holding bitcoin in a self-custodial wallet gives you full control over your bitcoin, and nobody can tell you any false story about your bitcoin because you are in charge of the private key.
I don't think its safe to do it while waiting for long term since we don't know what will happen to the exchange also as if that exchange would able to exist for more decades. So its better to safe keep our bitcoin balances on our wallets since there's nothing more safer since we have full control of the balance we have.
People need to remember always that Not Your Keys Not Your Coins since for sure they realize that those staking decision is truly risky on their side. I know some wants to earn more balances but actually putting it on exchange to earn something is somehow bad or risky decision they could able to do. People should not forget about what happen to FTX and Mt.gox since the incident of scamming might also happen to their favorite reputable exchange.