There Are So Many Reasons People Lose
There really are so many reasons people lose.
It's very much why 2 people out of 1000 succeed.
Most don't care. Some care but are lazy. Some just don't get it. It's so many reasons, but the result is the same. Did they achieve the outcome, or not? Code is a good analogy: the output is either 1 (success) or 0 (failure). That's all that matters, in the end.
University, marriage, etc. are all achievable outcomes, and if someone didn't achieve them, they lost.
Because, more often than not, if someone (no matter how impressive they may seem in that moment) failed at something that was achievable, they won't be a winner in the long run.
This is why selective universities are important. The baseline human being is simply a greater average.
This is probably why Google only hired people from selective universities in the beginning. It's a very good filter in stuff that matters (intelligence, social skills, hard work, etc.)