At the risk of getting shot from all sides, my take is a little different. I currently own a public golf course and have owned private clubs in the past. A couple thoughts:
1. At my public course, we see plenty of millennials. Tons. It's an affordable, fun course in a big-ish city. We also have lots of kids. Lots and lots of kids.
2. Not everyone is the same or joins clubs for the same reason. This will be a very hard fact for some of you to grasp. Not everyone joins a club to be able to walk a Coore/Crenshaw design with $1,000 leather carry bags. The clubs that I previously owned were affordable(ish) clubs in major suburban markets and . I could generally break down why people joined based on their age (but obviously there are exceptions, so don't start whining if you do not fit perfectly into my categories).
a. Age 23-35. Almost exclusively single men who played a lot growing up and still play a lot. They join a club because they play multiple times a week (what with no family and all) and the discount on dues makes joining a club a great economic decision. Also like the better conditions and and getting out of the public golf jumble. They generally join based on the course and the cost. This group might represent 5%-10% of new members.
b. Age 40-50. Mostly married couples. They join because Mom wants the tennis and they want the pool and the activities for the kids. About 50% join as social members and many upgrade later to golf. Or they join as golf because Dad wants to be able to play more golf, or he wants to use it for business. Course is not very important, most join based on location, cost and quality of pool/tennis/fitness. This is probably 50%-60% of new members
c. Age 55-65. Kids leave the house and/or primary breadwinner retires/slows down giving them more free time. Course becomes more important, as does dining. 20%-30% of new members.
d. Age 65+. Retirees looking to become more active. Dining and social calendar very important, course needs to be playable. Generally they join where their friends are already members. 10% of new members.
3. So, if the question is, why aren't millennials joining clubs, its because they, and the people before them, are in their 30's and do not join clubs in large numbers and never have joined clubs in large numbers. Other than a few single men, young people don't join clubs until they move to the burbs and want the suburban lifestyle with the kids on the swim team and Dad getting in 9 if he gets off work early. Millennials don't meet that criteria. Other than a tiny group of hardcore golfers, Millennials mostly play public golf. I'm sure they love Sweetins Cove.
If you want to criticize my fellow GenXers, that is a different story.