Regarding "everyone knows" - right! Does "everyone know" this about sports betting apps? If no, then they should. If yes, then no problem requiring unambiguous disclosures.
this can also be spun in a positive way: if that does ever happen, the bookies are literally forcing someone to quit when they are ahead! isn't that considerate of them.
unfortunately, i think sports betting platforms just have many strong arguments that controlling bet sizes in this way is fine.
Of course the entire business is built on creating the belief that a user can make a ton of money. Due to this mechanic, this is an actual lie.