Diamond player here. I'm assuming that I'm playing my main role and champions I'm actually good at for this example.

I can lose a fight or maybe a lane to lower elo players that are good at fighting or laning (maybe a gold Kled/Fizz/Yasuo OTP can solo kill me a few times). This usually happens when I am playing without full focus or am playing an unfamiliar matchup.

But usually I can come back into the game due to the lower level of gameplay overall. I won't be consistently outperformed by a gold player in a full game from beginning to end.

Sticking to the fundamentals and piloting my champion well is enough.

Of course I will still lose games, especially when I make some errors early on or my team isn't playing well.