It helps to pass time 
Lol there are many less expensive/not at all expensive ways to time pass like watching television,gaming, playing outdoor games etc..why do you find gambling as time pass?, you could get addicted really fast if you spend much time gambling.
Sports gambling can be used to pass time. Unlike casino games where you can play as many game as you want, a sports club usually play once a week.
If you are a fan of a sports club, you can bet on your team to win while watching it.