I think Bitcoin may help in this regard, but it is not necessary to involve mining in the process. You can buy 0.1 BTC for each of your cousins and then check what they have one year later. IMO Bitcoin is the best example on how important to save rather than spend on unnecessary things. I was doing this mistake many times in the past, I mean spending BTC by exchanging it for fiat. And now I say to myself: "Look, that bottle of wine you bought for $10 2 years ago after exchanging 0.04 BTC for fiat, actually costed you much more. You'd have $180 now if you didn't do that.