Why don't people just listen to music on their iphone why buy a ipod?

I know some mobile devices aren't good with organizing music but the iphone is good with that so why?

They want to show off.

Maybe some people don't have an iPhone. Maybe to save phone's battery/memory space.

I do it to conserve the battery on phone

Good question I think it's just for rich peole to show of how rich they are.