I still haven't read that source about dota 2 but personally, I think it's addictive because it feels sooooo good when you win. It brings the worst of you when you lose, but when you win, it feels really good, it's so satisfying to win a hard match, competitive or not (i play a lot of turbo, feels addictive anyway). After all, if we only felt bad when losing and didn't feel as good when wining, we wouldn't come back. Or at least, I wouldn't. If another game frustrates me, and gives me nothing in return, I leave it