You don't have to stake money for it to be a bet. You can bet on items, simple things like being right and receiving respect.
Betting is a part of gambling, but you can bet without any money. Friends often bet each other that they can do something and they get respect in return, or they get to eat the last candy or drink free beer at the expense of the loser.
You can bet from time to time without being a gambler, but a gambler is not someone who bets for fun. Usually this word is used to describe serious players. A guy who bets on one football match a month is not really a gambler in the full sense of the word.