It's the Dunning-Kruger effect, it's not just true about games and competition, but everything in life. Here's a link. https://en.wikipedia.org/wiki/Dunning%E2%80%93Kruger_effect
Also, as someone who spent about 14 years in the competitive fighting game community and recently gave that up; no one who has ever lost lost because their opponent was better than them, it was the game designer's fault every time. Additionally, every victory you ever scored was because you were just flat better than your opponent. As stated above, nobody every had an "off" game. You deserved to win every time, and never deserved to lose even once. At least, that was the common belief by about 90% of the community. Eventually this attitude by the majority of players drove me away from the scene.
Keep in mind I'm talking about a game that's 1 v 1 (same as chess) where you literally only have yourself to blame...yet somehow manage not to. Imagine how much easier it is to refuse to learn the concepts necessary to get better when it's a 5 v 5 game like League and there's 9 other people you can blame.
It's something everyone needs better perspective on, but the internet culture we have now is not pushing people toward rumination and introspection, instead just instant reaction and blame. As a result, it's almost impossible to have fun in a competitive environment anymore because people don't understand these things.
