Very good question of course - the incentive for not leaving will be the support for their posts from fellow members, and also not to miss out on future, guaranteed lottery wins. Keep in mind, each member will be a proven content creator, so they will care about both their reputation and securing long-term support for their work - if someone leaves after, say, two winning rounds, they will have effectively stolen 10 000 SP of curation power from the group, all of whom would be very unhappy about it, and could lead to systematic downvoting of their future work.

We hope to screen out anyone who might be so desperate that they would give up a future of guaranteed returns, for a quick couple of grand.