Like Vinny aid most teams probably do less than 5 events a year. It's a hobby. I try to do between 5-8 each year. I figure cost to me is about $5k. Last year I only did 5 and cut cost a bit and broke even with my GC and a few 1st calls. I use between 5-12 vacation days a year to compete. So I consider it part of my vacation budget. I have no sponsors. This cost does not include equipment.
And a lot of teams will do a little informal "personal chef" work on the side to make some cash. One good party on a weekend can bring in $500 to 1k. I do not cater as that require permits and inspections. Of course that's another weekend cooking so it usually means 1 less contest.
Retired competition cook. BBQ mentor.