As a miner (or a sub-node), you have to buy transit (bandwidth as a certain speed for a certain period) in order to operate. I would expect that as a miner, you have more inbound traffic consuming transit than egress because of how the block propagation works. Given that you only pay for the 'greater of' the inbound or outbound, this 'lodsidedness' can give you a pricing advantage against a competitor who does not. Let me give a example and hopefully this helps. Miner A: I pay $100 a month per Mbps (notice speed not volume). My ingress ends up costing me $1,000,000. My egress would have cost me $600,000 but I don't pay for it because my ingress is so much more. I then find enough blocks to cover the $1,000,000, my operating expenses and then I have $10,000 left over for profit. Miner B: Exactly the same, however spots the opportunity to serve data to clients as well. Now they can sell blockchain data using the excess egress for an extra $300,000. As a result, they are now 30x more profitable than the competing miner without paying anything extra. What happens if the egress exceeds ingress? It is greater of so they will pay more for the egress but nothing for the ingress. Subnode c: I want to sell blockchain data, I get the exact same deal as miner B, so my revenue is $300,000. However, I still need to pay for transit. The transit ends up costing me $600,000. So whereas Miner B ends up much more profitable, competing on a head to head basis as a subnode, I actually end up losing money. Does that make sense?