UFC has a rapidly growing global presence, Muay Thai doesn't to the UFC's extent. If MMA comes into Thailand and gets more popularity...it won't hurt Muay Thai, but they risk losing a certain % of the fanbase maybe to MMA.
Just a thought.
Could be the amount of Muay Thai fighters crossing over to MMA too.
Miesha Tate / Ronda Rousey / Rick Hawn / Ian McCall / Mike Pyle