I kinda doubt your opinion of his abilities matters to him.
The man is a whiz at poker and, for the first time in his life, he is a celebrity for playing a game that, in his youth, was very hardscrabble, back-alley, dangerous, illegal and not respectable. He is on TV, people know him, people admire him, he makes money from that both directly and indirectly. He's clearly enjoying it. He seems to still be doing well at high stakes -- although one never knows for sure. Many known pros have gone bust at times. He may not want to go there again.
The only reason for retiring from, say, grueling tournaments is his health. My guess is that he gets staked to most tourneys, but, dang, they are long and hard. And, for many pros, the tourneys take time away from the cash tables where they make their money. (The plus to tourneys is that, aside from the cash, if you win a big one or a few big ones you can possibly get sponsor deals and outside-poker income. And you get the extras that come with poker fame, however shaky that might be. Doyle already has those things, and his name is a draw so will likely keep getting those things as long as he wants.)
My guess is that Mr. Brunson will be playing until he physically cannot do it any more. Hats off to him, and long may he reign.