If investors are enthusiastically in disagreement about the potential of a company (both the buy + sell sides), it's probably better for the company's valuation to stay private. It blocks out any negative opinions' effect that you'd have if public via investors shorting / betting against the company.

This probably leads to an overly high valuation it wouldn't hold up to on the stock market, though, (i.e. Uber) so then the company feels pressured to stay private until they can justify that overly high valuation. In Uber's case, though, they'll keep raising money at absurd valuations and keep the cycle going.

Palantir is an exception: If they were public and had to disclose much information, their value would plummet, so it'll likely stay private in the foreseeable future.