It's perfectly possible the bet is good for both sides, just as it is possible the bet is bad for both sides. You are equating money with utility. A 1 in 1000

It's perfectly possible the bet is good for both sides, just as it is possible the bet is bad for both sides. You are equating money with utility. A 1 in 1000 bet that I'll get 1001 times my money back if I play with my life's savings is a terrible terrible bet for me to make even though it has a positive average return. It's also a bad bet for the bookies because they will lose on average. The larger the cost the more likely it'll be worth taking out insurance.