Earlier quoted context omitted.
Negative thinking feels bad. Maybe he's never actually experienced it. A better explanation is needed.
The statements "negative thinking feels bad" and "negative thinking feels good" are not contradictory at all, though they may appear so. The way in which it feels bad is obvious, but the way in which it feels good is not, and takes self-observation and honesty to detect. The effort is well worth it, though, because it provides a way out of the conundrum. If I'm only aware of how they feel bad, then negative thoughts…
I hypothesize the reason humans perform worse after failing a hard question versus passing an easy question is that by keeping yourself down, you avoid getting into trouble claiming a higher status in the tribe than you can pull off if it comes to a confrontation. But you feel bad so that you keep looking for an opportunity to claim the higher status/more resources position. Perhaps explaining this (if it is true) and that this doesn't confer any benefit in our current environment would be just as effective.