as you said bonus hunting has the risk of losing all funds to reach the wagering requirements and for arbitrage betting has the risk of account being banned from any sportbook as was the case with some people in the past.
Not only bonus hunting, but all forms of activities that risk money in the gambling industry carry the risk of losing money and of course every gambler who bets has understood and can accept the risk of losing money.
But there are not a few gamblers who cannot accept defeat and then chase victory to return the loss.
Arbitrage Betting has become a ban in most of the casinos so one has to avoid such way of betting to stay out of trouble.
But it needs to be underlined that there are many gamblers who continue to make arbitrage bets secretly and they do everything so that the casino team doesn't know about them.