I'll fill my time-honored role of Devil's advocate and write up a TL;DR.
I can
sort-of believe that Dobson has suffered prolonged mental anguish from the result of the water spray. I place Dobson and DSP in a unique category of what I call a "careercow", which is a Lolcow who's primary method of entertainment is failing at a career they could potentially be successful at. DSP carried a large fanbase and if he had treated it and responded to it better, he could be a big player still. Dobson, back in the day, also had a very serious cult on deviantArt. He was a massive inspiration to developing artists on the site, and it's the reason why ForeverPandering made the videos in OP: Dobson was a false prophet to him.
Dobson has repeatedly drawn comics of himself at panels suffering from anxiety. We all get anxious, even if we're handsome Swedish men with yarn dolls. The thing is, I think Dobson convinced himself that if he started attending conventions and selling his comic books in person, he would make a name for himself. His dream of being a professional artist would come to fruition and he'd pan out being a freelance artist drawing only what he loves. That did not happen.
Instead, he got

. Some little kids pulled a prank on him and embarrassed him in public. They probably even damaged his comics with some water. It was a
cruel joke, and I personally would have been livid. So what you potentially have is a massive build-up of intense suspension, a hopeful impetus pushing him out of comfort zones to attend events that could lead to dream fulfillment, and a massive letdown spearheaded by some kids with water guns.
So now, a hopeless and oafish aging man with no spouse and no real career, he thinks back to the waterguns as symbolic dampening of his match. Not gonna lie, I feel for Dobbles. I wish he had gotten better at some point.