Blackjack can be difficult to win at because it is a game of both skill and chance. The odds are stacked in favor of the house, and the rules of the game are designed to give the casino an edge. Additionally, players must make decisions based on incomplete information, as they can only see one of the dealer's cards.
It's definitely possible to play blackjack for a living. It takes hard work, determination, and self control, but we are living proof that you can make a living counting cards at blackjack (not to mention the 100 people we hang out with at the blackjack ball, half of which are millionaires thanks to the casinos).
