Our biggest mistake starts here: using centralized exchanges in the decentralized system.
Yeah me in personal never giving away or even tell anybody in my circle (friends, family, etc) about the cryptocurrency that i possesed because there are so many things will happen if it's all about money. So we better keep ourself and place our wallet in a safe area that we are the only one that can access it.
In terms of safety you may be right but think about the other side. If you die in an accident, will not there be someone to access your wallet. The funds you have collected for years will be buried with you. Think about it without wasting time and teach everything to the person you trust.