All kinds of people participate. When I was an almost full-time volunteer at county headquarters I was also a night shift security patrolman at an Air Guard base.
We live near a large military base. The largest number of people at our local Republican Party are professionals and retried professionals followed closely by business owners and retired business owners, followed by retired military officers and their wives and then a gaggle of attorneys who take every opportunity to remind the rest of us that they are smarter and better than we are.