It's NATURAL for me to spend as I do!
Turns out that my brain, rather like the devil, MAKES ME DO IT. Spend too much, that is.
It turns out that one's shopping habits have a lot to do with how active two centers of the brain are, the "nucleus accumbens, a region of the brain with dopamine receptors that are activated when you experience or anticipate something pleasant, like making money or drinking something tasty," and the insula, a "region of the brain activated when you smell something bad, see a disgusting picture or anticipate a painful shock."
The New York Times reports on the science behind spending.