It's a very good concept , at least it has instant use cases that is rewarding. There used to be a project like that also called Gym reward that pays people when they exercise. Seems it has also gone low. These are good concepts that needs to be handled by devs that are professional and passionate about it.
A good concept does not mean that it can be applied in practice. Many projects are created from groundbreaking ideas, but not many can achieve success. Most fail to implement after launched for 6 months and 1 year.