Great question and the answer might not be all that obvious. One explanation could be the Diderot Effect. The Diderot Effect states that obtaining a new possession often creates a spiral of consumption that leads you to acquire more new things (click button below to read the full story of Diderot and the Diderot Effect).

For example, you buy a new dress and now you have to get shoes and earrings to match.

Or you purchase a CrossFit membership and soon you’re paying for foam rollers, knee sleeves, wrist wraps, and paleo meal plans.

New car? It’s almost a cue to accessorize with things you may not have even had in your previous car–like a tire pressure gauge, a car charger for your cell phone, an extra umbrella, a first aid kit, a pocket knife, a flashlight, emergency blankets, and even a seatbelt cutting tool.

Life has a natural tendency to become filled with more. We are rarely looking to downgrade, to simplify, to eliminate, to reduce. Our natural inclination is always to accumulate, to add, to upgrade, and to build upon.

So, what can you do about the Diderot Effect?:

• Reduce exposure – Buying less new items can be simple as unsubscribing from commercial emails. Or calling the magazines that send you catalogs and opting out of their mailings.
• Buy items that fit your current system – For example, when you purchase new clothes, look for items that work well with your current wardrobe.
• Buy One, Give One – Each time you make a new purchase, give something away. Get a new TV? Give your old one away rather than moving it to another room. The idea is to prevent your number of items from growing.

There’s a very addictive quality to buying new things. By recognizing that and taking a few simple and pain-free steps, you can to stop the buying new stuff snowball from turning into an avalanche of new purchases.

For a full summary of the Diderot Effect, including more solutions to curb new stuff spending, click here.