Higher pay: When a campaign comes up with a higher pay rate members prefer to move to such a campaign for more money.

Change of campaign rule: When the rules of the campaign change, it might not suit some members. Some campaigns can decide to remove or add some boards to their campaign posts which some members might not be comfortable with

Longevity of the campaign: Some members might decide to leave a high-paying campaign to a lesser one because they believe that the low-paying one will last longer. Some members cherish longtime campaigns rather than high-paying ones.

Change in ideology: Change is what is constant in life, a member might have changed his ideology or perception about a service. I have seen some persons who feel gambling is immoral but later change their thinking because they gained more knowledge.