Roulette is beatable, even with losing odds.
Bet on black. If you lose, bet the sum of all your previous bets x2. Example:
Bet $1 - win = up $1, lose = down $1
Bet $2 - win = up $1, lose = down $3
Bet $6 - win = up $3, lose = down $9
Bet $18 - win = up $9, lose = down $27

Unless you lose every single 49/100 roll for eternity, each roll allows you to finish up. Whenever you are up, you stop, or start over at $1 until you have as much money as you want.