I had someone in an off-site RP, after a shocking plot revelation given by the main NPC of the RP, decide to leave the place and have fun at the arcade. Then after he did that, he said he couldn't post anything since he was stuck at the arcade, and after I asked him to follow up on his arcade adventure since he wanted to do it he deserted the RP, complaining that he was railroaded when I NEVER DID SO, and in fact encouraged him to continue with what he set up. Posted in the RP for years too, so it felt real shit of him to suddenly leave like that.

Also, I've seen an arena try-hard bitch about something an opponent did, and when the GM stepped in and made a compromise of the situation he also left. And then I've seen people write absolutely garbage sheets like they typed it up in a drunken stupor in five minutes, filled with emoticons and with the character looking crimson-haired an yellow eyes and built like a bodybuilder at the age of 16. He also wrote his robot to be a repair-guy but with numerous superfulous devices and shitload of weapons thanks to the additional arms he wrote to himself. When the GM refused it and demanded for changes he started bitching in the thread with long paragraphs of crippling and nerfing while making no attempts at fixing his shit.