There are many reasons why blackjack is often played at 21. The most obvious reason is that it is the only game where a player can earn a guaranteed win by hitting on 21.
Other games, such as poker, can have similar odds, but the possibility of losing a hand makes them more risky for players.
Another reason is that 21 is the most common number in casino games. This means that there are more opportunities to winnings when playing blackjack than any other game.
In addition, casinos favor games with higher payouts, so they will increase the house edge on games with a higher percentage of hands in which the player loses.
Finally, many players find blackjack to be more entertaining than other card games. This is likely due to its high degree of randomness and the potential for big wins or losses.
