The sad fact is that humans can never be happy for any length of time. It is how our brains are wired and a result of evolution. Even if a person lived in a paradise and had all their needs and wants provided; one of two things will occur - Either that person becomes bored or they wonder 'hmmm, I wonder if x,y or z could be better in some way?' and then trying to improve on perfection.
If humans could ever reach a state that would guarantee happiness we’d still be living in caves and having 10 children so 5 make it to adults.
Progress requires dissatisfaction with the status quo.