It’s one thing to troll and call out a professional fighter online, and it’s another thing to actually show up when challenged back. And more often than not, the troll will get some form of respect just for showing up, regardless if they get badly beaten up in the process.
This exact scenario was something UFC fighter Kevin Holland dealt with recently, when a random individual consistently pestered him online, looking for a fight. “Trailblazer” (a.k.a “Big Mouth”) finally obliged, paid for the young man’s hotel and meal when he got to Texas and sparred with him.