Card games have ever-changing odds and outcomes. The game of roulette cannot be adjusted mid-spin. Card games carry an element of skill. With blackjack you can split cards and double down; with poker, you get to swap cards and select hands. Card games, therefore, have a far lower house edge with blackjack being the best at 1.47% Roulette is still a fair game because you have bets that as even odds, so your chances really are 50/50. These bets are High/Low, Red/Black, and Odd/Even.