In practice that particular thread likely required all kinds of environmental details to occur - details the entrepreneur might not have noticed at the time, might have forgotten about later, or might be discounting as unimportant.
However, at the end of the day, you are taking a risk, it's a gamble. What stops most people is the fear of failure. This fear isn't necessarily unwarranted. As the author points out, he has a previous failed startup. Most people don't have the drive to work hundreds of hours after work and possibly invest their own hard earned cash in a project they suspect deep down might not actually pan out. I know I find it difficult.
Still, I don't dislike these stories. It's good if it inspires people to take (calculated) risks, and it is possible to learn from failures. Though I would also say that yeah, there's probably some self-selection going on. The people out there with 2 or 3 failed attempts at monetizing side-projects probably don't feel super eager to write a blog post and tell us all how we can improve our lives by following in their footsteps.
But there are many, many people who do have the circumstances to make it happen, and who would benefit from it, but who make wrong choices and waste their time elsewhere. Those are the people who the article is intended for.
Speaking more broadly - The fact that this business strategy isn't immediately available to every person on Earth doesn't seem that fruitful of a point to make. Why does this come up every time someone posts about anyone doing anything entrepreneurial and succeeding? What is the message for disadvantaged people in our society? "You have no chance of succeeding because of your circumstances; give up now"? Somehow, this external-locus-of-control  viewpoint seems very attractive to people to the point that they actually want to spread it memetically. And yet it's been pretty well demonstrated that this style of thinking is actually harmful to people to who engage in it.
Even for many of the people who can't immediately carry out a strategy like that in the blog post - many of them could, with some time and preparatory action, get themselves into a position where it's possible. Consider someone who lacks skills, connections, and experience. They cannot reasonably expected to start a company right there and then. They can be expected to get a job, spend a few years getting experience and connections, move up a rung or two, then perhaps quit and go entrepreneurial. If that's out of the cards, they can likely study to move towards the point where getting a job in the target field is feasible.
Yes, there are people who are so downtrodden that they can't even take steps towards getting into a position where they can do better. And some people won't get all the rewards they deserve, in some moral sense. But the great majority of people can do something to improve their lot, even if it isn't exactly like what goes on in this blog post.
Even consider the author of the post - he didn't just start this business from college; his success here depended on the years of work he did before and the connections and experience he built from that.