Primedice is one of the most trusted site and if you are going to accuse something, you need to provide some proof rather than telling that they are faking the stats
If they provide access to site data-base(they don't). such that one can find the fake users who always bump the site total wagers. (no proof but fact).how do you think a gambling site would run, with government money.

I am not commenting on his trust gaining strategy
if site lets users to invest and uses any trusted third-party Random Number Generator ( where site/owner don't have direct access to seeds ) then it could be a perfect system.
so they cannot fake site wager. and cannot create fake winnings
