I think you need to keep reading.
It helps if you look at it this way: every hand you play costs you money, simply your bet size times the house edge. A $10 bet on a game with a 0.5% edge costs you 5 cents
Every. Single. hand.
If you're just fooling around online like a civilian, then the key is to limit your bet size and number of bets so that your losses are manageable. If you're bonus-whoring, they key is to ensure that the bonus is worth more than you expected loss (and you don't overbet from a volatility standpoint).
It even works with card counting. Every hand you play with a disadvantage costs you money, the plan is just to bet much more when you have an edge.
