As for (1), there is the added nuance of not wanting to hurt their ego: "if I'm not successful, it's because I started from a below-average level." But there are few things I dislike more than this very human and very popular form of cowardice. And it also works, which makes my dislike moral and not utilitarian.
Recently, I was listening to an interview with Jon Jones (the very famous and very talented MMA athlete), in which he related that he used to do something crazy a few days after his fights, maybe spend a night out partying and drinking, so that he would have the excuse card (for himself, not for others) ready if he happened to lose his next fight. It worked for him—-he is probably the greatest MMA fighter of all time--but I still found his approach a bit cowardly, weak, defensive.
I spent many years practicing jiu jitsu and got my black belt a few years ago. Now, it is common for fresh and not-so-fresh black belts to say that when you are a black belt is when you realize you know nothing about jiu jitsu. Like any social meme, it is hard to distinguish "true thinking" from "going with the flow"--everybody says that, why should I do otherwise--but I certainly know a lot more about jiu jitsu than I did when I was a white, blue, purple, and brown belt. This is not to say that there is much to learn and that I may be below average among practitioners 10 years younger than me and above average among those 20 years older. But why not be honest with ourselves and others, without thinking about ego bruises or the sympathy we may receive?