> Aggregate categories are invalid
In the search for a single factor, groups of factors seem like invalid entries.
Talking about the influence of chance on the outcome of a given set of circumstances in the universe, we're getting into free will / determinism here (and that's probably not going to be a terribly productive discussion) so I'll move on to your other point.
> I think it's harmful
I'll concede that in a vacuum you'd be right, but we're not in a vacuum. Making decisions based on factors you know about is different from consciously ignoring external factor outside your control or assuming that the factors you control are weighted more heavily. I think this conclusion of yours about my argument, though, is based on the "awareness" vs "control" confusion from above, so my overall conclusion is that we're on the same page.
Grit is most certainly a group of factors.
Nobody is taking about free will or determinism. You are introducing that as a straw man.
We are not on the same page. Weights or not, you are advocating intentionally miss-attributing effects to causes that are under your control. Making reference to 'confusion' doesn't change that, and looks like another straw man.
Given that you advocate self-deception, your response seems consistent with your policy. I salute you for your consistency.
I disagree with your refutation of 'luck' in point 1:
I agree that luck is an aggregate of 'all factors beyond your control', but I do not agree that conscious awareness is sufficient to place things into your control. Therefore, luck includes all factors beyond our control, whether we are aware of them or not. It's perfectly reasonable to group these together under a category. If your argument is that aggregate categories are invalid, then you must apply the same logic to 'success'.
More importantly, I agree with your second point, but I think it's harmful. Confidence based on self-deception is known as hubris, and leads to deceiving others and thus doing harm.
There is no need to deceive oneself in order to feel confident. That simply comes from an accurate sense of one's capabilities and the situation one finds oneself in.