The rec who's up $400 and keeps saying "just a few more hands" is stuck in a session he should have already left. His focus is gone. He's playing to protect his stack, not to win more.

Why they do it

Players who are way up and overstay start making defensive decisions - checking back value hands, not bluffing spots they should, folding too much to aggression. They're not playing poker anymore. They're guarding a number.

The adjustment

Attack them with aggression. They'll fold more than usual. They don't want to give back chips. Use that against them.

What it's worth

A scared winner at the table is one of the best bluff targets in the room. A well-timed bet in the right spot gets folds from hands that would have called you two hours ago.