It sounds to me as if you think it's luck, and one cannot be good at making an idea happen: Talking with users, UX design, writing software (or hardware/something), marketing, setting a vision, hiring the right people, building teams, talking with the press, etc.
... and thanks to such skills / good judgement, succeed once, and again.
No, it's luck, is the impression I get, when I read what you write. — Maybe that was not what you meant and I'm reading things wrongly.
I don't assume that, actually. I think that (of course) one can do all those things well and the startup still fails.
I'm thinking we're slightly talking past each other:
1. I had a look at your HN profile, and notice that you've founded First Principle, and "We Start, Help & Fund Fantastic Businesses". This indicates to me that "all day long", you spend time with startups that do close to perfect execution of their startup ideas and businesses.
Still, some of them fail, others don't. And, then, from your perspective — it's mostly luck, who will succeed and who won't. Since everything else is done really well / close to the best possible approach.
2. Then there's my perspective: I was recently in StartupSchool, and the people there and I too, can be pretty clueless about how to build startups. In our cases, I'd think it's often doing-things-in-the-wrong-&-clueless-ways that kills a startup. Or not talking with possible customers, pursuing the wrong ideas, building things no one wants.
\* * *
I'm more used to startups failing because of not-so-good execution.
Whilst you're used to "perfect" execution, and startups instead succeeding / failing because of things they cannot control, Luck.
\* * *
With this in mind, now what you wrote, makes sense to me.
... and thanks to such skills / good judgement, succeed once, and again.
No, it's luck, is the impression I get, when I read what you write. — Maybe that was not what you meant and I'm reading things wrongly.