The challenge of a random company posting about their experience at YC is the same as what you'll hear about HBS - it's always anecdotal and tied to the personal outcome of the writer. Are there people who spend a shit ton on HBS and don't return that investment soon enough? Sure. Would it make sense to go to HBS? Depending on where you net out, it can be the best or the worst investment you've ever made.
The nice thing about YC is that you're not investing your cash, but equity. If you have the right business/team/timing/execution, then the cost of equity will be high, but you'll do better than you ever expected so it's all good. And if you don't do well, then your equity wasn't worth much to start with, and you essentially got the HBS experience for free without any of the debt.