Im not sure youre even gonna come close to 15000 participants. Seems like a waste of time for you to put up these threads where you want 10000-15000 users to join.

What needs to be clear is What happens if 15000 ppl dont join? How will these users that do join know if 15000 ppl joined? You just expect them to start sending you the bitcoin on the 5th? You gonna refund them their pennies when 15000 ppl dont join?