Security, base-level platforms, and wallets

I know my measly little coinbase funds are safe enough as is, but at what point (how much dollars) are you no longer comfortable with a platform such as coinbase, Venmo, cash app, etc. housing your assets that you would rather them be in a wallet (coinbase wallet or other).

As an amateur crypto investor I’ve not worried about it yet, but the thought of complicated wallets and sending (a lot to me) money digitally around is intimidating, but I see a lot about how bad say coinbase wallet is so just trying to get a little more information before investing more with mistakes