Why did they pick someone so mentally absent?

He'll either step down or be dead with in the next 1-2 years, then Kamala can take his place.

Because he was the least hated by their lemming voters. So the party leadership made Biden their nominee.

Because his. career was over and he had nothing to lose if they got caught, probably nobody half credible wanted to be involved. They did get caught but it doesn't seem to matter anyway. The whole system seems to be failing and it's getting worse and nobody with any sense seems to be able to get things heading in the right direction. Wrong policies, disastrous outcomes and then further terrible decisions.