Earlier quoted context omitted.
The problem is this: the house always wins. Casinos, online sports books, the lottery, all of it is designed such that all but quite literally a lucky few will lose money. If you understand this properly, then, yes, there's absolutely nothing wrong with it being a form of entertainment , but that means you need to go in thinking about cost per hour instead of any notion of leaving with more than you began with. This…
The house does not always win in online sports books. I personally know some quant minded people that have been banned or backed off from a dozen or more online sports books because they are crushed by any nontrivial understanding of price/probability and arbitrage. They do make a lot of money from people who bet for fun or based on their perceived knowledge of the particular sport.
That's the house making sure that the house are always the winner.