Why would you forget a seed with a million worth of Bitcoin in it?
I don't have that much but I will never let my seed be forgotten or lost, the same with my private key. Either way, if that is transacted, it will be a talk of the community. It is true that Bitcoin is volatile, that it would dump and pump in a certain time but with a lot of people supporting cryptocurrency, I don't think it is that bad. People are taking advantage of those movements to earn some profit in the long run.
Not all of the investors of bitcoin or crypto currency as a whole are like you. There are a lot of incidents that investors lost their key, their files, showed their private key to everyone, or sent their bitcoins into the void. Incidents happen but I do agree that this is not the reason for these people to avoid it, there would be other reason.