#4 Actors aren't allowed to take too many bumps in the ring
One of the richest actors in the world, Dwayne "The Rock" Johnson is also considered a great wrestler. He is passionate about this sport but the sad reality is that he isn't allowed to wrestle anymore. Technically, it's his contract that prevents him from wrestling.
If actors get injured, it'll cost the production team their time and money. This is why they (the actors) are legally bonded not to do anything that might injure them. The Rock injured himself a few years ago while wrestling, and because of that, he doesn't risk his body anymore.
A WWE Hall of Famer isn't a John Cena fan. More details HERE
The is the similar case with John Cena. He has joined the cast of several movie franchises. And him getting injured while wrestling would be the last thing producers want to see.
Even if Cena wants to wrestle (as he says), his film contracts would prevent him from performing. He is taking new projects at a rapid pace, and this might trigger his retirement sooner rather than later.