I'm going to go against the grain.
Boxing isn't like singing, where modern technology can mask shortcomings in your technique and your capabilities are much more subject to the vagaries of subjectivity, and as such, people with no palpable talent can flourish. In the boxing ring there is no such hiding. If you're a charlatan, you will be punished in a discernibly painful and public manner.
At 38, he's opened himself up to ridicule and humiliation in a way that a manufactured pop artist would never be exposed.
Assuming he's put against worthwhile opposition, then good luck to him, I say. At his age, I made a decision to take a gamble and change direction in my life in a pretty significant way; some people were supportive, others scoffed - it worked out ok. To those that scoffed: go fuck your mum's ****.
Given all the above, if it comes off for him, in any meaningful way, it will be an unbeatable feeling for him. That, and his ego, are why he's doing this, safe in the knowledge, no doubt, that it won't do his profile any harm, whatever the outcome - and he won't be sweeping the streets.
If nothing else, it demonstrates to me that he's got a MASSIVE pair of bollocks - and for that reason alone, I wish him all the very best. Anyone who backs themselves like that, deserves a degree of admiration, even if they are a Camelgobbed ****.