There’s no cognitive dissonance in believing both of these things at the same time. The non-paying users are freeloaders because they’re gaining value with no intention of paying for it. The service isn’t compelling enough because, despite all of the attention it’s getting, it can’t attract paying customers.

They’re both causative to some degree, but from the entrepreneuer’s perspective, there’s nothing that can be done about human nature— you just have to account for it when designing your offerings.