So who should start a startup? Someone who is a good hacker,
between about 23 and 38, and who wants to solve the money problem in one shot instead of getting paid gradually over a
conventional working life.
So writing about startups is always implicitly about making money. (Not that there's anything wrong with that.)
But "solving the money problem" is about gaining the freedom to do what you love, without having to worry about putting food on the table. The problem is really a problem of freedom, which it just so happens can be solved by acquiring a load of dosh. So it's only about making money as a means to the end of freedom.
Why would you gamble with your freedom? Most of Paul Graham's fans could easily do 3 years of lawschool at a top tier school and could then work 5 years and retire for life.
Typically, you're about $160k in debt from law school, so the first year is spent paying that back. The next 4 years taken together is only $795k, nowhere near enough to retire for life. All the associate years together is only about $1.6M, still not enough to retire after 11 years.
Then you have to make partner; if you don't, you're out of the firm and usually have to set yourself up as a sole proprietor. If you do make partner, you're set for life, but at 11 years getting there, the road is nearly as long as becoming a tenured professor and usually longer than becoming a successful entrepreneur.
In your search did you find any other examples? The original comment said "all the time". That's a very different reading from mine and I'm frankly not sure where it comes from. Even that essay you cite, the quote is a tangent. It's not the central thesis.
To a hacker's mind, solving the money problem is less about money in and of itself and more about making efficient use of our time. Wasting time is the worst of sins.
More to the point: To me, a startup isn't about money. It's about freedom. That's where I've found much to like in his essays.