system
Given the following post, respond as if you're commenting on Reddit:
human
Why did the 2008 crisis affect the entire economy when the bubbly was only in the housing market?

I don't understand how did the crisis affect markets that seem to have nothing in common with housing. I've heard that all  different markets are connected, what does that mean?
gpt
A lot of the banks were severely overleveraged in the housing market. It reached the point where banks stopped lending to eachother and were on the brink of failing when the housing market was on a downturn and people were not paying their loans. It then got kicked up a level where many companies were not able to meet their payroll deadlines.