I've heard the saying "There is good luck in chess but there is no such thing as bad luck" - meaning you can win because you were lucky that your opponent played poorly, but if you lose it is because you were outplayed.
that.. doesn't make any sense.
<<Also there's absolutely no randomness involved.>>
So for practical purposes that's incorrect. It's correct only in an idealised setting where the best decisions CAN be made.
It is correct, period. There's just no randomness in chess. Not being able to make the best decision is not caused by presence of randomness, but by a lack of skill.
In your opinion. But where the best computers cannot solve it, randomness is therefore involved.
Incorrect. There is always a best move in Chess.