I could be 100% wrong but I don't trust primedice from my experiences and what I've seen with others, that's just my honest opinion. Call it bad luck or whatever but I see alot of really strange behaviour, uncanny bad luck for alot of people, not just losing the bets but the timing of losing the bets and the crazy losing streaks just at the right time. The provably fair thing is so complicated to most users that they could be screwed over but just can't understand it so accept that it's fair. All I hear is 'ask dooglas' he'll say its fair, you mean that other guy who also runs a dice game site? And how do we know the primedice verification websites aren't run by affiliates? Again I could be 100% wrong but this is just my honest opinion how I feel.
My thoughts are they are taking 1% rake they have no need to cheat unless they are a small dice site. This logic alone isn't 100% conclusive though. The volume of bets players put in at dice games its very hard to win long term so maybe thats why your results are bad idk.