That is definitely suspicious but you or me and no one can prove it so we should just let it go :/
You have to take into consideration Stake is the biggest crypto casino, probably the biggest casino in the world period when it comes to how much is wagered there on a regular basis. When you count Prime Dice, they've been around longer than anyone, will process withdraws for hundreds of thousands USD instantly and millions in minutes. They are obviously making a shitload of money, which makes the thought of scamming someone even for tens of millions of dollars a dumb idea.
Basically, if you want to gamble for millions, there are really only a few options where you don't have to worry about running up a balance so big that the casino would have to decide between going bankrupt and scamming you. Stake is one of them.
You also have to consider that the people with these ridiculous amounts of crypto likely don't want their identity known. That includes both their real life identity and online. Think of how many click bait articles would be written the second anyone confirmed who they were. If they want to gamble big, it make perfect sense for them to just hop from new account to new account and it makes perfect sense for stake to allow them to do that. I wouldn't be surprised if the AABB account owner is done with that account already.
You also have to put the amount of money in perspective. Stake knows how much their players are going to gamble in general, they structure the payouts so that everyone gets somewhere between a few hundredths and a few tenths of a percent of their wager back.
Think of it this way:
(Edit: I did some stupid math initially and my numbers were off by either a decimal or a comma, just went and fixed them)Weekly boost is a .1% refund on your total wager. $1 for every $1k wagered.
Second and third place in the race paid $120k and $80k.
The players that finished second and third wagered over $120 million.
That means that during that period, they each were paid over $120k just in weekly boosts.
The 10th place racer received almost $50k in weekly boosts before getting his $10k race prize. And remember, you don't just get weekly boosts. There's monthlies and reloads and other bonuses as well.
Point is, the money looks huge to us normal people, but when you put things in perspective, the race prizes are peanuts, which is why accusing Stake of some elaborate scam so they can steal a few hundred k from players they regularly bonus millions is ridiculous.