No Bitcoin-based protocol can handle more than 20M users per month
OP makes the implicit assumption that all lightning network payment channels are p2p in which case the 20M users per month upper limit is true. From what I understand, the plan is to have a network of supernodes which settle on the blockchain. Users will interact with these nodes instead of true p2p. Lightning network opponents argue that these supernodes will become mini banks in some ways and will need to follow KYC norms. While it's possible to do p2p payment channels without interacting with any third party, the high transaction fees make it impractical. From the Lightning Network paper [0] :> If all transactions using Bitcoin were conducted inside a network of micropayment channels, to enable 7 billion people to make two channels per year with unlimited transactions inside the channel, it would require 133 MB blocks (presuming 500 bytes per transaction and 52560 locks per year).Notice the 2 channels per year. These 2 channels will be opened with a supernode (operated by eg- Coinbase, Gemini, Blockstream etc). I glanced through the document but they don't seem to acknowledge the requirement for these supernodes.It's hard to cut through all the FUD, trolling, memes and propaganda to get to the meat of the debate, so I'm not too sure my understanding is accurate, feel free to correct me.[0] https://lightning.network/lightning-network-paper.pdf