How did bitcoin network transacted $90 billions just yesterday? By spending more energy than the entire world has ever produced?
A fun thought experiment is to see just how limited the throughput of Bitcoin is. Suppose the Bitcoin enthusiasts were to get their wish and Bitcoin becomes the dominant "currency". If every person on the planet were to make a bitcoin transaction once if their lifetime, that alone would be too many transactions/second for the network to handle.
Some say Litecoin will be used for that but I doubt it. Coins like Cardano or IOTA will be used for transactions. I'm not sure about Cardano but with IOTA you can transfer a fraction of a cent (or no value at all) without fees (that doesn't mean everything will be always fee-less).