To be honest, I have never reviewed such charges, is that when I do sports bets, I usually do not sit still and start playing poker and blackjack, and since I saw that there were no relevant amounts that I was losing, I did not review the clear gallery it is logical somehow the house must win by placing those services.
They earn with sports betting and take profit margin from the bets from side a or side b. It just so happens that you cannot notice it because your whole amount bet is still there and won't change once you bet and it's only increasing when you've won already. And when there's already a winner, that's when they're going to take their profit margin and will be distributed to the bettors who have won those bets while taking a chunk from those bettors who have lost and that's why they've got some percentage and those odds that we see from stake and other sports book are different.
The biggest method they are making a profit is the fact that they are like an exchange, where they are taking profit on the difference. There are nearly always bets on both sides, so that means when one team wins the other loses, and that results with sportsbook getting money from one side and giving some of it to other side. Sometimes this means they are making a lot of profit, and sometimes it means they are losing a lot of money with it, but they always end up profiting because of the way they calculate the odds.
Long story short they make in multiple ways, from margin, from charges, from difference, basically they always make a profit no matter what the result of the game is, it is just how the business is made. Casinos and sportsbooks (house) always wins in the long run, there is no work around that to make sure you win every time, it is impossible.