Because, if you are trying to, that's already a very widely known thing, it is not something people hide? I mean casinos do have a house edge that they literally tell you about or sportsbooks do have odds that they share you with and all of those have a bigger chance for casino to make money.
This is not some "maybe you will be rich" type of Hollywood movie, people know that they will lose their money if they play for long enough time. They will tell you that you are going to lose in the long run.
Nevertheless, people believe that once in a life time deal, maybe just once, only once, they will hit big and become rich. No one believes they can constantly beat the casino but maaaybe they can get them only once for a big win like a huge jackpot and got away with it.
People are not losing in long run on sport betting
Sport betting is about reading stats
Based on that punters are wining in long term
Problem is when punters are wining bookies are suspending accounts
One guy last time won 100/1 on horse racing
his stake was 100 pounds
Bookie paid him after 10 days when case was famous and press was writing about that
So bookie had only two choices or pay or risk to lose customers
Other thing is that UK gov doesn't care of children protection
If shop owner will sell alcohol to kids than he will face big problems
Bookies are holly caws and they know about it