This isn't even a joke... Like, I keep hearing my conservative family members express that they can't vote for "someone with dementia". Glossing past Trump's many, many, many senior moments, it comes down to the fact the president is supported by an entire cabinet.
If Biden gets poo brain, he's going to rely on his cabinet. If Trump continues down his poo brain path, he will never rely on a cabinet (especially since it's full of yes-men). He will just let the dimentia drive him, just like he did in his first term.
E.g. Airports in the 1700s, convincing everyone covid isn't that bad prior to a vaccine, posting "white power" to his Twitter, tear gassing protesters for a Photo OP where he holds a Bible upside-down. I could go on, and on, and on...
But sure, let's all pretend Biden's old man brain is a real serious problem. Because sometimes he... ::checks notes:: falls on stairs, and fumbles words.
These clowns voted for fucking George W. Bush, by the way.