> If an individual is winning a lot of money from a bookie repeatedly because of these bad initial prices, then it is a sign that they might have a better model than the bookie, and so it is in the bookie's interest to ban them
I don't think this follows. If an individual is winning a lot of money repeatedly in this way, it is a sign that the bookie should give their bets a lot of weight when adjusting prices. But that information is something the bookie might want.
If bookies want better prices they can pay for prices from places that have good models. Or they can buy / build their own models. What you're suggesting doesn't make sense from an economic perspective.
I don't think this follows. If an individual is winning a lot of money repeatedly in this way, it is a sign that the bookie should give their bets a lot of weight when adjusting prices. But that information is something the bookie might want.