I never buy stuff I don't end up using. I know some people who used to have a compulsion to buy the things they looked at in the shop, it's quite common.
The reason is they see something they like and get the impulsive feeling which takes them through the buying process. This can be a tremendous problem for people with credit cards because they don't appreciate what they are doing until after they have done it.
That's just a compulsive process that has been learned at some time or another. Some have a little impulse and for some people it can be a big expensive compulse.
The solution is to learn how to buy so only what is needed need be bought.