Bitcoin isn't really a protocol, though. It's a network, a specific network of users, miners and a unique and limited unit of account. Protocols can create multiple networks. Nostr could have private Nostr within your TCP/IP network for your company or family. It's a protocol.
You can't have your own Bitcoin, without it becoming something else, so it has an icon.
Bitcoin is a decentralized money protocol in the same way that BitTorrent is a file sharing protocol.
Both are protocols.
In the tcp/ip stack it is at the application level at the same level as http, smtp, etc.
Bitcoin defines a protocol for that, and you can use that part separately from Bitcoin and it works, like Litecoin or forks of Bitcoin. That's not the part we're actually referring to when we say 'Bitcoin'. That's not what the icon means.
In Nostr, the icon means the client. Though maybe HTTP should have an icon. Maybe it doesn't mean anything at all regarding having an icon. Maybe we need an icon for a protocol for making social apps.
You need an icon because it will represent your public key with which others will be able to communicate with you regardless of the client.
