Probably an agree-to-disagree situation on the luck part (I do think the form of your opponent, their readiness to respond to your tactics, etc. can be 'luck' up to a certain point, although in fact it really is a skillset, basically), but I agree with Tyranitarwiththehardname here that psychology is a basic part of every and any single game, and it becomes more and more important in direct confrontation.
This can be seen in three ways:
- Psychology during a match
- The way one thinks about the opponents skill disregarding the current match
- The way one thinks of their own skill
I think that the latter does kick in here (or at least possibly kicks in here). If you think 'I'm not doing what I'm supposed to do, how can I still win games, etc.', and you try to rush adapting your game style rather than thinking through what you're doing thoroughly, you can make poor choices in adapting your playing style. This also can happen during a match - if you're annoyed because of some bad play, you often try to make up for that, but very frequently rush to make even more mistakes, especially given your anger/annoyance.
In Dutch, the German term "Angstgegner" (which sort of translates into nemesis) has become part of everyday speech. An angstgegner is basically an opponent who has beaten you over and over again, even though their skill is usually even at best, and it is not unusual that their skill is even lower. Still, the psychological penalty you pay is high, this is actually a thing. Mainly because you think that you maybe have to adapt to their playing style, which is often not that good.
Although this is certainly not purely dominion-based, psychology plays a part in every competition one participates in, for better or worse. The best way to contest this is concrete analysis - what are the core mistakes and how do I change them, and definitely not rushing things and adapt your style and strategy on a whim.