> The range proofs are verified by monero nodes or the transaction is invalid, so it is sort of like asking to audit that all bitcoin transactions are correctly signed. The cryptography for Bulletproofs and its implementations are audited by cryptographers, which you can read. Just run a monero node and count up all the inputs from the block reward, which are public. That's the supply.

Thanks - I'll investigate this further

> The low block size and resulting high fees aren't an intentional design decision. It's not "optimized" for anything except the network conditions of 2010, because that's the last time satoshi changed it. Satoshi clearly intended for the block size to be raised[0][1]

Bitcoin is what it is. It makes no difference what Satoshi had envisioned for it. It turns out that it's an excellent savings tool/reserve asset - an (ideal?) store of value.
It's optimised for large size and long duration because the transaction fees are independent of size, and it has a capped supply with predefined issuance curve.

> The difference between gold and bitcoin is that gold doesn't require a constant value transfer to miners (in the form of inflation or fees) in order to be secure, gold can just sit in a vault. In 10 years down the line if the mining reward is too low (coinbase keeps getting cut in half, transaction fees will need to increase to accommodate), miners will sell off equipment and attackers can buy them up.

It's not true that bitcoin requires continuous fees to remain secure. Any transactions more than a few blocks deep in the current blockchain will remain secure forever - even if the network shuts down. If it doesn't shut down, there will be transactions, and the small blocks (~7 txn/sec cap) see to it that transaction fees increase with demand for transactions. The more new transactions there are, the more secure those new transactions are - a positive feedback loop. The only way the transaction fees would be too low is if bitcoin has already failed and there is no demand for it as a store of value. The incentives will actually be for the wealthy (individuals, companies, countries) to use it all the time, as the fees become insignificant for large transactions.

> it recreates money printing unless you are using lightning. If it is just some payment processor you don't have a payment channel with (like PayPal as you suggested) there is nothing stopping them from doing fractional reserve banking on the other side and giving out loans.

Correct, but they will run the risk of an old-fashioned bank run, so there will be a lower limit to the reserve fraction, unlike with fiat central banking where there is no reserve requirement (infinite money supply)

> People can self custody now because fees are low. If more people use bitcoin, the fees go up and it becomes impractical. Using bitcoin for everyday transactions is the whole point bitcoin was created in the first place.

Again it makes no difference why it was created. It is what it is, right now. If regular people can't afford to onboard, so be it. Rich people, large companies and countries will be able to, and it's this large injection of wealth that will make it extremely valuable, rather than piggy banks etc. In fact the banks used by the masses would likely store those people's wealth in bitcoin behind the scenes, even if they don't offer bitcoin accounts to the customers themselves.
The reality is that if banks don't provide on-boarding, higher-level networks like Lightning (with channel factories), fedimint (https://river.com/learn/terms/f/fedimint/) will offer a path for the masses to onboard in the future.

> This will just give you proof that the custodian hasn't moved the outputs, which is sort of flawed. It doesn't tell you anything about ownership.

It tells you a lot about ownership - you would be able to see your own transactions on chain. You can't transfer ownership of bitcoin without a transaction and that would be visible to the legal owner (the customer) and would immediately trigger a run on the custodian - likely putting them out of business, never mind the legal consequences, which is a great incentive for custodians not to rehypothecate it (understatement...)