When it comes to looking at a subset that doesn't join a club or a country club, it's important to look at the reasons why people join clubs in the first place and look into further detail into the subset.
Why do golfers join clubs?
1. Distance - the closer a club is the more likely to join2. Atmosphere - Culture, Ambience, vibe, whether friends are there etc3. Quality of course - design, conditioning etc
4. Price5. Other - Clubhouse, practice area, food, other facilities etc
Two things that are mentioned as barriers are always cost and time, however golf courses are large maintained areas and will always have a cost associated with playing. Golf courses aren't generally big profit earners so they are hardly gouging customers. For the time factor golf is played over a large area and will always take time to play. Whether a round takes 4:20 instead of 4 hours isn't really a barrier. If anything joining a club gives adaptability in time, the golfer can play 4, 6, 9, 12 holes etc in the time that's available to them.
If we look at the 'Millenial' generation and see why they don't joins clubs it is because the generation of early 20's to late 30's have always been golf's lost generation. Many have mentioned it so far in the thread. That age group has the distance issue, they go to college, they get a job, change a job and the uncertainty about where they will be located in 5 years is a barrier into joining a club. The price is also a factor, finding a home, getting married etc all cost money so this is the other barrier. Both these are not unique to the 'Millenial' generation.
Should clubs start chasing the millenials? I don't think so, a few craft beers on draft and music playing on the range is not going to get a club a flood of 20 something members.
For clubs their location, course, clubhouse, facilities and even price is basically fixed. The one thing they can work on and tend to ignore is atmosphere. Atmosphere is key to retaining and growing membership, look after your current members and more will come. When looking at service it's not having 4 guys at a bag drop in the car park, it's knowing the membership and taking a genuine interest in them, knowing when Jim likes to play, that Jane is just back from a golf trip and to ask her about it, that George who normally plays 3 days a week but hasn't been around the club for 4 weeks and giving him a call to see what's happening. This is what clubs need to do to get members to stay and more to come and yes this would include millenials.
A further thing to do is to develop junior golfers and focus on making them golfers for life, most junior programs are looking to develop elite golfers. Develop a love of the game amongst the junior golfers and they are golfers for life. Even when they hit the lost generation of 20-40, some will continue to play frequently as golf is their passions, for the others even if their passions wains and they just play a couple of times a year, when they are more settled in life they'll come back to the game.
In short to get Millenials to join, look after your current members and develop a passion for golf in junior golfers.