I think we'll need more examples then just Buffer. Everyone knows Buffer is a successfully bootstrapped company that grew kind of big but not massive.
If the author gave five other examples, then there's a case, but pointing out the one known example doesn't provide enough evidence in my opinion.
A separate point on style and punctuation: too many em dashes in the wrong places.
> What would make Buffer — a good investment?
No need for an em dash here.
> And, if you want to start a get-rich-slow SaaS fund — what is your target maturity?
Same.
> What if, at end of the holding period — investor sells the Buffer stake at market valuation?
Replace em dash with "the".
> But wait… that perpetuity — is a “paper valuation”.
Remove. The ellipsis could be an exclamation point, though it could be in the "personal style" bucket.
I would suggest removing every single em dash and practicing writing without them. They can be useful—for providing inline examples or explanation, for example—but should be used sparingly. Commas, colons, parentheticals, and semicolons can cover most of your use-cases.