Lot of truth in what JK says.Whether the annual dues are $1000 or $10,000,those members are paying because they believe this gets them something that the non-members can't have.
Dues paying members will overlook some non-member play--even if the green fee is less,or frequently substantially less,than the members' average cost per round.But there's a limit.
When a club concentrates too much on short-term revenue,there's the risk of waking up one day to find yourself A) overly dependent on outside revenue,while B) your dues paying members walk out the door because their dues checks no longer buy them anything special.
My guess is a lot of clubs are caught in this cycle.