The base layer of bitcoin is more of a settlement layer; Lightning Network and other layer 2 features allow for super fast and super cheap bitcoin payments.
Instant Payments. Lightning-fast blockchain payments
without worrying about block confirmation times. Security
is enforced by blockchain smart-contracts without creating
a on-blockchain transaction for individual payments.
Payment speed measured in milliseconds to seconds.
Scalability. Capable of millions to billions of
transactions per second across the network. Capacity blows
away legacy payment rails by many orders of magnitude.
Attaching payment per action/click is now possible without
custodians.
Low Cost. By transacting and settling off-blockchain, the
Lightning Network allows for exceptionally low fees, which
allows for emerging use cases such as instant
micropayments.
You cannot argue that “Bitcoin is money” if, in order to do any of the money stuff, you need to add something that is explicitly “off chain.” Bitcoin itself plainly can’t do it and LN could just as well be a layer on top of anything else. It’s main purpose is to make Bitcoin seem like it could be useful some day.
And yet we’re years in and virtually no one uses LN as money despite lots of people having a vested interest in making it seem viable. I’m sure some people trade it back and forth but nobody is buying goods and services with it outside of as a gimmick.
You cannot argue that “Bitcoin is money” if, in order to do any of the money stuff, you need to add something that is explicitly “off chain.”
Bitcoin already does the money things as you call it, being able to send any amount of value to anyone else without requiring 3rd parties.
You can send $1 million worth of BTC anywhere in the world in minutes and the fee right this very minute is $5.94 for a high-priority transaction. But if you had any doubt of ensuring the transaction gets into the next block, you could easily start with a fee of $15, which is a trivial amount for a $1 million transaction.
But for use cases where the fees and speed are problematic—you might need to wait 10-15 minutes for a transaction confirmation—there's Lightning Network which clear instantly and the fees are fractions of pennies.
The "off-chain" comment is misleading; Lightning's payment channels require a base layer transaction to open and close them; it's the transactions that happen in the channel that aren't on the base layer because the entire world doesn't want to see every cup of coffee anyone of us purchases on a global immutable blockchain.
Once one of us (me or the other party in the payment channel) have decided to close the channel—like paying a tab at a bar—the end result of transactions hits the main bitcoin blockchain.