Dan-the reason the pool needed to buy 40 tickets is obvious. Because otherwise naphtali is just buying a ticket himself and wouldn't even bother collecting the 5 cents, and then why is he sharing it with us.
The reason to join a pool is that it's fun, and its an excuse to buy another ticket. I'm in 2 pools, and have one ticket myself. I'd actually most prefer to win my family pool, since then we'd all be rich together.