Don't underestimate the power of immediate convenience.

And for that matter, there are a number of people who effectively live paycheck to paycheck - "If I buy it online, it wont show up until next week, so I'll wait until I need it and buy it locally" (I understand how credit works, but many people dont, or dont have credit for some other reason). Additionally, there are a sizeable number of people who cant, or wont buy anything online.