It is not good to hold your coins on exchanges but hold them on a self-hosted wallet. This brings the responsibility of how not to lose your seed phrase because if you lose your seed phrase you will lose your coins.
If there is a natural disaster that flood your town or an earthquake that destroyed the building your seed phrases are, what are the other recovery means that you have in place for you not to lose your bitcoin?
We should backup the seed phrase in a way that no matter what happened, we should still be to have access to the seeds phrase. What are you approaches to make sure that no matter what happened, you will have access to your seed phrase if you are still alive and your brain is functioning properly.
I know that saving vital informations like the seed phrase online is very risky cause of hackers the best place to save is inside a safe, write it on a paper then put in a safe or crest it on a metal plate since that is resistant to water and fire outbreak or you can choose to use a hardware device like flash drive for storage but in a case of natural disasters like earth quake, hurricane or flood, that's if the person survives the natural disaster, i think saving online comes in handy but you'll have to secure your mail with a very strong password and even use a 2 factor authentication method for security to avoid hackers from penetrating easily into the mail. You person can easily login and get your seed phrase so far the brain is functioning properly as you said.