I get that it's possible I could have a stroke and forget.
Or Alzheimer's. Or dementia. Or trauma. Or sepsis. Or COVID. Or a thousand other things.
But I like the idea that if I were suddenly to find myself in a foreign country and needed funds. I have them with me. In my head. All I have to do is find a bitcoin ATM. Damn cool if you ask me!
Agreed, that is cool. However, that doesn't mean you
only need to store the seed phrase in your head. I have memorized the seed phrase to my mobile "day to day spending" wallet, so I could recover it without my phone in desperate situations, but I also have the seed phrase backed up on paper in two secure locations.
Relying solely on your memory is incredibly risky, not just for the seed phrase you have memorized, but for all your different "encoding" and "misdirection" methods. Even if you have the right 24 words but in the wrong order, you are looking at 600 billion trillion combinations. pooya87 is right - we see users regularly who have come up with their own system and can't remember how to reverse it, locked out of their coins forever.
Write down your seed on paper, store it somewhere secure, write down your passphrase(s) on a different piece(s) of paper, store it/them somewhere else secure.