Why do we buy compost?

How did everyone do for compost this year?
I didn't buy any and still have stacks of coir and about 3 bags of compost bought 2 years ago.
For the GH tomato pots I used a mix of hotbin compost and some bagged compost. Contrary to the blurb, the Hotbin does not kill all seeds - tomatoes and some sort of squash germinated in the hotbin compost. It takes a lot to kill a tomato seed, unless you want to grow it when it might struggle!
I'm going to collect some molehill soil from the garden and mix it with coir to see if that gives it more body for seed propagation.

I know a bloke who used molehill soil in his raised bed for growing showleeks. When it rained it turned to something similar to concrete!