Those are true enthusiasts...very wealthy enthusiasts.
I always respect those that drive these machines as opposed to wiping them down with a cloth diaper in a climate controlled facility and posting regular videos on you tube of their under carriage.
I'm wondering if Jay Leno has ever raced at a Goodwood Revival (or paid a driver to race). With all the cars he owns, it would surprise me if he didn't own a car from the circuit's original period—1948–1966.
It depends. A lot of old racecar drivers still race in the events and other times there will be current and former racecar drivers at the event that owners will have race their cars for them. I dont think there is money involved, but more a, "Hey, want to take my car down the track?"