Luck is always a factor although the amount you need will be diminished by the skills, experience, available time and means, as you point out.
Many young developers are in his position though. They have a modicum of skills (he admits he can only get by in PHP), they have some experience (they're in a job, at least, or they've done some travelling), they have time (they don't have kids yet) and they have the means (they are living with their parents and they don't have a mortgage to pay off). All of these were true in his case.
I don't think it's a get-rich-quick story, as he did spend years on a previous side project that didn't work out, mainly due to the limitations of his skills.
There is value in all of these stories and no one on HN, I hope, is going to believe in get-rich-quick although they just may be motivated by these ideas to get on with it. Perhaps all these little business spin-off side projects just suit me personally so that it's less that I'm optimistic and more that I enjoy them.