Top Reasons Why Members Leave

Lack of Open-Mindedness
Everyone wants to be heard and have their ideas acknowledged. When members begin to feel that the decision makers of the club often waive their ideas aside in order to follow through with an already set strategy, they begin to feel undervalued. As such, they slowly begin to lose interest in the club and its activities. As a solution, always try and incorporate the best parts of their suggestions. New suggestions can only improve your current strategy and help you achieve your goals.
Vision/Mission
Look at your club's current mission statement. What is your club's vision for the future? Is is exciting? Is it something your members are proud to share? Do all members even know what it is? A mission statement really defines what your club is about and your vision defines the future of your club. Who came up with the mission statement and vision? Chances are, when your club members choose what it is they want to achieve as a club, they'll work towards making it a success because they'll believe in it.
Exciting Tasks & Projects
Team Dynamic
Does everyone in your club get along with one another? How is your team dynamic? When everyone gets along and are on friendly terms with one another, you can be sure that they look forward to club meetings and events because they enjoy each other's company. If there's a bad seed that causes friction with more than one member, deal with them! You may think that they do so much for the club and you would hate to lose them, but think about how many members you turn off by letting them get away with bad behaviour. Ensure your team dynamic is strong. To do so, plan events that revolve around building your team dynamic, and find ways to allow members other than the usual leaders play a role. After all, a strong team equals success!
Trust & Shifting Priorities
When members promise to fulfill a goal or have a task completed, trust that they will deliver on their promise. You've got to give them enough time to complete the task at hand, instead of reassigning it to someone else. For example, if you've issued a challenge to a group of members to fundraise and collect a certain amount of money by a certain date, believe they will do so. If you see that they won't reach their goal by the set date, offer them advice and help rather than enlisting another group to complete the task. If members feel like their club supports their initiatives, they'll attempt to do more for the club, otherwise, the impression that is left on them is that the club isn't interested in their efforts at all.
Authority
Although you cannot exactly 'tell' your club members what to do and how to participate, the board can still outline club expectations from all members. Anyone who is part of an organization, knows there are guidelines to follow and will appreciate suggestions and observations made on becoming active members.
Everyone wants to feel valued. When people join clubs or an organization, they do so to be part of something and to contribute towards something. When they feel that their participation or efforts are not acknowledged, they begin to feel as though the organization they want to be part of doesn't appreciate them. As a result, they feel that leaving the club would be a better option.