In particular, despite the risks, I would say that putting your Bitcoin in Coinbase is far safer than physically holding your own keys since the risks of that are far greater than storing your keys with Coinbase. Holding your own physical keys for significant amounts of your savings, in fact, is downright dangerous and I wouldn't suggest anybody do it, despite any systemic risks with Coinbase.
This is simply irresponsible. There’s no insurance if Coinbase goes bankrupt. Instead of taking responsibility for your own money --Bitcoin's very purpose-- you’re trusting a broker that has every incentive to gamble with your funds.
The right approach is to learn how to properly set up an airgapped wallet and educate yourself on security. Relying on trust in others is unforgivable, when history is filled with breaches of that trust.
Storing your wealth in the safest available way is certainly not irresponsible. I think it would be the opposite.
Meanwhile, storing your own physical keys involves risks, and people lose their Bitcoin this way all of the time.
You are basically making the case that you should fly your own airplane to travel even though, statistically, you are far safer in a commercial airline. If you know "exactly what you are doing" then you can, individually, perhaps beat the odds. But generally that's not the case.
Your airgapped wallet can be breached by any rubber hose cryptoanalysis, and the idea of storing one's life savings physically in their own home, which could get invaded by men with guns who would come and kill you for this money, is pretty terrifying to most people.
Understand, by the way, that all of the rules change between "small" money and "big" money. I talked about this in the
Anon Paradox: the way you treat the cash (e.g a "cache") in your personal physical wallet is very different than how you treat your life savings--or at least it is for most people.