We have more cards to count and multiple deck is not as favorable as single and double deck. We also have to convert to a True Count to adjust our betting and playing. Bad players cause us to lose If this were true, I would never play blackjack again. I am always playing with people who do not know the correct basic strategy for the game. Therefore I should not win if this were true.
Some people play a little bad, some very bad and some absolutely terrible.
This is one of the biggest mistakes a player can make. The casinos love people who take insurance. If a person were to take insurance every time that they had a blackjack. In order for a person to break even with insurance, you would have to guess correctly 1 out of 3 times in order to just break even on the insurance option. Only if you are card counting should you ever take insurance.