Well, some people will be glad to flaunt how much they've saved/gained, if they see it as socially acceptable or advantageous.
If social media has proven anything to me, it's that a targeted subset of society can be pressured to do something through peer pressure or ridicule, when there is enough "noise". Negative reinforcement works magnificently when someone/some group is publicly humiliated for something they should have had control over or done differently.
There is a downside to it though... "shaming" someone is frowned upon, so it has to be done generically...
A positive reinforcement method should work too, but as we can plainly see, it doesn't.