1. Rick says that there is an assumption that bitcoin can't...

1. Rick says that there is an assumption that bitcoin can't scale this is incorrect. The issue is that to scale on chain you have to increase block sizes as you increase block sizes small operators drop out and you have centralisation if you get enough centralisation all you have done is duplicate mastercard /visa and you have lost one of the prime reasons for having a blockchain that being the elimination of a trusted third party . Once you have centralisation through a trusted third party you are dependent on the integrity of the third party and its ability to keep your assets from being interferred with by a fourth party( government). Always remember that the both Nakamoto and the cyberpunks were reacting to
a. the GFC and the way it hit ordinary people through banks
b. a general lack of trust in the financial system

Looking at it positively they were attempting to create a currency that is censorship resistant and privately controlled i.e. governments could not fool around with it like they do fiat . Individuals wealth could not be seized .
It is because of these characteristics that after the cyberpunks who have an anarchistic streak had adopted it, the next group to adopt it were liberterians who although not truly anarchistic have a minimalistic approach to the role of government.

It can clearly be seen then why one definition of BTC is that

it is a collective insurance against the failure of fiat.

This insurance is being used in countries where fiat has collapsed .If you do not want BTC for this purpose it is questionable why you would want it at all as it is not and never has been a guaranteed source of gaining wealth although many individuals fooled themselves into thinking so particularly in the fourth quarter of 2017.Now many of those same people are showing the attribution theory at work as when they do well it is because they are good at trading but when they do bad it is all a fraud .
In order for it to work as an insurance against the collapse of fiat as it has three attributes functions
1. it is a store of value
2. it has transaction ability
3. it can not be interfered with

The store of value is determined by supply and demand . Although I do not know the mind of Nakamoto , the late Hal Finney or any of the cypher punks I doubt if they saw it being used in the speculative way that has occurred particularly in the last quarter of 2017. I regard what happened then as the equivalent of us all taking our house insurance policies and passing them back and forward for more and more money it could only end in tears and for some has.
Until the value gains stability based on a genuine supply and demand where the limited amount of coin is a major determinant of price and the other cause a genuine buying as a backup insurance against the collapse of fiat this attribute will be unreliable .
2. Transaction ability. You might ask why it is important to have speed if its main use is when fiat has collapsed and if taken only for its original purpose my answer until someone convinces me otherwise is not that important except that there are two types of fiat collapse
a. total collapse i.e. Zimbabwee
b. undermining of wealth by inflation ( many are prepared to live with this some are not)
It is group b who need the higher speeds as they essentially want to have BTC to gaurd against government caused devaluation of personal wealth while using the BTC to transact ordinary business .
The difficulty BTC ran into was at it became more popular transaction times and costs soared . No other crypto has had to deal with this sort of volume the nearest is ethereum and it is now trying to find an answer to these questions plus the question of lost funds which has caused what I would describe as a civil war among ethereum developers ..
The seemingly simple way to fix the problem was to make larger blocks which is what BCH did however it did not come anywhere near the benchmark standard of mastercard /visa for speed . Bitcoin and Bitcoin compatible currencies implemented segwit now followed by lightning. Segwit has now reached about 30% adoption and costs for transactions have crashed . They should go even lower as further adoption occurs

https://blockchair.com/bitcoin/transactions

while bitcoin cash is still stuck at the below

https://blockchair.com/bitcoin-cash/blocks

Lightning is only just out of development while the head of the company that released it has expressed the hope that there would be a cambrian like adoption it is still possible that due to the decentralised nature of the BTC chain it may take some time .
The advantage of lightning is that it is far faster than Mastercard or Visa
Bitcoin before segwit did 3 to 4 transactions per second
Pay pal does about 193 transactions per second on average (as someone who uses it at work this is a frustratingly slow experience )

Visa does 1,667 transactions per second on average and can handle 24,000 per second

https://altcointoday.com/bitcoin-ethereum-vs-visa-paypal-transactions-per-second/
BItcoin cash with larger block sizes does i think about 8 transactions per second

Bitcoin with Lightning is expected to hit millions to billions per second

https://lightning.network/