On Bounties
Bounty participation is usually limited to several hundred people per social network, because the expense allocated for the bounty promo is almost always fixed. In bounty announcements, this is called the "bounty pool". The pool is held in escrow by the bounty manager and gets divided among the participants. This means that the lower the total number of participants, the better the payout for each. It's also the reason why you are not likely to ever hear of bounties unless you specifically look for them.