5yo beats 3yo at everything they do.
3yo is utterly inconsolable every time. Furious sobbing rages.
They make everything in to a competition. I have limited these eg "no racing up the stairs to bed" and "no more races today" sort of thing.
It is getting very, very wearing.
5yo is sometimes kind and lets him win, but this isn;t really the answer.
How do I get him to understand that sometimes you win, sometimes you lose and it's okay and we can try again? Any attempt to broach the subject incurs another screaming tantrum.