During a conversation he had with a fan, he was saying how "IT's FAKE" and he meant no disrespect, but that's where the mistake comes in. Dana White DID disrespect not only the fans, but also the wrestlers who saw that tweet.
Here's the one thing to keep in mind. Professional wrestling is SCRIPTED. It's scripted just like your favorite movies, tv shows, and video games. The pain is real, and the injuries are real too. Wrestlers, especially in WWE work a schedule similar to MLB. Major difference, no offseason. Meaning, they have to work year round and travel a lot.
For those that don't wrestle in WWE, they're known as those who wrestle in the independent circuits. The pay is far less that what their WWE counterparts make, but they use their own expenses and travel to the cities just to entertain the fans. Some have to work day jobs just to get by.
There are those who follow both wrestling and MMA. I happen to be both. Granted, I do not watch MMA as much as I used to back in the day, but I respect both industries and want everyone to succeed. When you're a public figure such as White himself, you pretty much have to "keep up appearances". Which means, any comment positive or negative, will make an impact. That comment might've lost him potential fans who want to follow the UFC. To paraphrase Triple H, that comment was not "best for business".