Casinos and online casinos love to perpetuate the idea that blackjack is the one casino game in which the house can be beat. They will even admit that you need a blackjack strategy to beat the house. And they are more than willing to perpetuate the myth that blackjack strategy is the key to beating the house.
And they would be lying to you.
It is true that basic strategy is a major tool against the house in blackjack, but it will not beat the house on its own. Playing according to basic strategy can lower the house edge to 0.5%. But players must play it perfectly, otherwise that 0.5% is not achievable.
Even if you are playing perfect basic strategy there will be times that you lose a round. This is because you only have a 48% chance of winning (ignoring pushes) in blackjack, even if you are using basic strategy. Think about it—if you have lower the house edge to 0.5%, the house still has the edge.
But casinos and online casinos will happily allow and encourage players that they cannot lose with basic strategy. Some brick and mortar casinos will even give players a basic strategy chart for free.
What they are hoping to see are players who believe that they will win every hand with basic strategy who then lose a few rounds and toss the chart away. Once they taught the chart away they are playing without strategy, and that means more money for the casino.
It is possible to lose rounds of blackjack. It is possible to lose them in a row. In fact there is a 14% that you will lose three hands in a row. It is just how it is. And casinos are hoping to bank on that percentage and what players toss their basic strategy charts away.
The best thing that you can do for your blackjack strategy is to understand that you will not win every single hand. Even card counters who are skilled enough to gain an edge over the house will still lose some hands. Stick with basic strategy and hang on through the hands you lose.