First send your seed phase or private keys to your emails, also use them to compose a little song only can listen anytime, write it down in your diaries, and makes sure have a google doc to save your wallet keys and other information.
This certainly not a bad idea because once you have your seed phrase online then it is not longer yours. It doesn’t make it any different with saving your coins on exchanges. People tend to trust too much on email and google doc but once it is compromised everything on it is exposed. Email one of the most vulnerable places to store your coins.
Everything comes with a risk and self custody is also without risk but it is better to lose your keys yourself than handing it over to hackers
You are right online is not the safest place to store the seed phrase, because it is no longer new that email can be hacked, and if hacked hackers have access to all vital information. We should not give all the trust to email because it is unsafe for storing privates keys. For me I think the safest place for a seed phrase is to record it in a book and put it in a safe . Their is saying, if you want to hide money from people, put it in a book because books are not attracted to people when they first site it.