Different thoughts

So I always have this issue with myself and I hate myself for it.Basically I’ll want something and be craving it,But then once I know I’m getting it or something.I change my mind and don’t want it and hate it.For example I want this new game and I’ve got money for it now,But all of a sudden I’m not in the mood for it and don’t want to play it or anything.Why can’t I be normal?