What is the culture/business-model of local MTB races and Gravel races?

[matticus]

I have no experience/involvement in these things! But I DO have experience with Time Trials, Cyclocross, Road-races/Crits and Audax.
(and this may not be the right board, but I tried ...)

How are MTB/Gravel run? Mainly clubs+volunteers? Event companies? Shops? Profit/non-profit?

Are the two categories generally the same organising people/bodies, or completely different groups?