By joining network, you can watch transactions and win miner bet(s) (1000 units) if you find a fawlty block. You can watch the 5 latest blocks on a chain and claim fork (rollback) if you find a fawlty block. As first dIscover of a fawlty block you win half of the miner bets from that block and any consecutive blocks. Your co-validaters share the other half. To mine blocks yourself you need 1000 units.