There is no such thing as a "professional" dice player in the matter of crypto dice games, which are provably fair.
You cannot beat the edge (except in the case of bustabit) regardless of how much bankroll you might have.
I don't think anyone needs the extra step of you proving your winnings... all you have to do is display your profit statistics across the accounts and prove that you own them.
I can show all of the accounts and prove that I own them. I understand your scepticism and its appropriate.
I also agree that the players can't beat the house, but it is also true that a player can beat the house, ask any casino operator.