system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: How do so many mattress stores stay in business?

I feel like I see so many in such a small area.
gpt
1. Everyone uses them. 

2. They sell them for a lot.

3. They can keep them for a while if they don't sell.

People don't buy mattresses very often but a mattress company can sell them for over a thousand dollars each. Unsold mattresses alo keep their value very well. A mattress that no one has bought for a few years can still be sold at the same price. And eventually everyone will buy a mattress or two.