Well, my train of though a week before the science fair went like this:
"Nah, Im not going to win stuff during that, might was well buy stuff now with the $100 I saved up"
Sure, but if there is nothing you want to buy, why try and find something you don't really want?
I once saved a hundred and forgot about it for a few years. When I had realized my former self saved money and now I had even more to use, I was overjoyed, and bought something I had wanted for a while.
Saving is boring but if you don't want anything its cool to do.