there's 1,000,000 validators (defined as a public key), but you can run multiple validators per machine. Most estimates that crawl the p2p network to index nodes comes out at like ~20,000 machines

doesn't invalidate your point but it at least shaves off a few orders of magnitude

and a single PG node is not a fair comparison, we're talking 100% uptime global networks. Visa does about 70,000 transactions per second - how many servers do you think they run across their infra?