WWE performers are already underpaid. They are non-unionized independent contractors who cover their own travel costs and get no medical benefits. Less than 10% of revenue is dedicated to talent in WWE, whereas it's around 40-50% for unionized sports.

https://wrestletalk.com/news/comparison-wwe-stars-greatly-un...

It's been reported there are performers who make more money streaming on Twitch than wrestling.

https://www.thesportster.com/news/zelina-vega-more-money-twi...

For UFC it's around 15% of revenue.

https://www.fightful.com/mma/report-ufc-fighters-received-ju...