I think it largely comes down to there being no benefit to the prion. It’s more of a lightly continuous sort-of-poison than an actual actor looking for its own reproduction. Viruses and bacterias existence depends on reproduction. Prions just kinda appear naturally from folding errors.
They don’t “want” to exist, even to the minimal extent of a virus, they just happen.
They don’t “want” to exist, even to the minimal extent of a virus, they just happen.