Penn had arguably the most natural talent out of any MMA fighter ever (literal prodigy in bjj, unbelievable flexibility and takedown defense, one of the best if not the best chins ever, heavy hands, etc) but he was lazy and squandered his gifts. He was too arrogant to realize this until it was far too late. Now he is trying to regain what he lost but he's too physically beaten down/mentally drained to compete anymore... yet he can't accept this and keeps trying to fight which causes him to decline more and more. He can't let go and if athletic commissions were legitimate organizations and not completely corrupt cash grabs, they would stop him