Bitcoin's ($BTC) security model is built upon monetary incentives to miners who ensure the network's transactions in return for a fee. Over time, a cross-over will occur where block subsidies switch to mining fees exclusively, an event Dan Held believes is actually a non-event given Bitcoin's strength. As the network effect adds more members to the pool, demand for block space will decrease the need for block subsidies while increasing miner fees. Comparatively, these fees are low for the settlement of large sums of money like international payments or shipments. A solid mix of physics and game theory have produced a self-perpetuating monetary experiment.