#4 Fewer dates to work
WWE superstars are on the road for over 200 days a year. Apart from the weekly TV shows and Pay-Per-Views, the stars are on the road in several Live Events every week.
For example, WWE were on a European tour this month. In those 14-odd days, there was a live event at least every other day for the stars, and for some, every single day.
One thing mentioned explicitly in the rumors that linked Dean Ambrose (Jon Moxley) with All Elite Wrestling was that he would have fewer days to work. And when a person has fewer dates to work with the same or better pay, is there any doubt on who he/she would pick?
WWE are a huge company, and they need to have these Live Events to keep the fans entertained and make sure they get to attend a live show at least as ticket costs for TV Shows and PPVs are significantly higher.
However, this takes a toll on the superstars, and many are on pain killers more often than not.