People just get that way in the game threads. They are yelling at the TV or venting at the bar, on their computer or phone.
And for some fans the agita is part of the entertainment. I know it is for me but that's also why I don't get worked up really. A reliever who puts two guys on base and then gets the save actually is drama/entertainment, with a more emotional arc than a perfect inning. Whereas an actual blown save, that's worth complaining about. The 2024 that the Diamondbacks and Rangers had, that was worth complaining about (though probably didn't hurt the Rangers quite as much since they already had a ring).
The thrill of victory is always sweeter when you've know the agony of defeat. But then there is also Mike Schmidt's perspective, of course.
