And all of that is paid for by the regular dues. So, for the cost of your yearly dues you can have maybe 6 turnouts at home, or access to pretty much anything you could ever want. Any money over the dues that you want to devote to the hobby you can devote to getting the rolling stock that you particularly like. You don't have to spend money on lumber, paint, lighting, track, scenery, power supplies, etc. At a club, you can focus on what you like to do, and the other stuff gets done by other members.
Many hobbyists find that keeping up with the layout they've built at home can be quite a chore.
It's much less of a chore if you share the maintenance with a large number of other people. Plus a club can afford some things that you might not be able to as an individual. For example, we don't have just one track cleaning car, we have whole strings of them. Try our N-scale layout. It will take you a full half hour to go around it, even at a good speed.