even sweepstakes conducted by large companies for their customers can also be seen as gambling. like two people watching a football match on television. they bet on the team to score the first goal, or the team to commit the first offense. and whoever loses will be hit on the head. it's a gamble even if not with money.
Gambling does not require money in playing actually this is a form of entertainment for all the people who would like to play before there's no money just a form of items they are using for trading or making a bet or sometimes nothing just casual rules that do they bet, like casual conversation, just making gambling of the team or players you would like to win. If you play you win if not its part of the game, people makes the gambling too much serious and become part of the business industry.
Maybe when gambling started when money was not fashionable, what they used to match were coppers, silver, gold, or things that were important to them in exchange for what they won.
This is probably what you mean, am I right? Though, I really believe that there are other gamblers who do it just as a hobby and nothing else.