The need for more pockets...

[Atma]

THAT'S WHY YOU ALWAYAS GOTTA /bUY  A LOT.

Also there are (generally) discounts for bulk purchases. 

I wonder why more people don't do this? Like, once you determine you know you love something, why not just buy a bunch up front and then never think about it again? 

I think it's because people want the periodic "distraction from the terror" that is afforded by having to restock. It's the same reason people go to starbucks every day instead of ordering a lifetime supply and just suppling from home as you wait on death.

In ordering a lifetime supply of anything, there's a sense of finality that is off putting. "If I buy a lifetime supply, this will be the last time I ever make this purchase"; you're connecting that moment of purchase with your inevitable demise.