The benefit of decentralization is not nearly large enough to outweigh the massive costs.
What does this even mean? How do you determine the value of decentralisation and what's its fair cost? Why do people (miners?) bear those costs then?
It means that the only "pro" of crypto over, for example, Visa or Mastercard or Venmo or any other means of transferring money/value is the fact that it is decentralized. You don't have to trust anyone, whereas with Venmo, you're giving a company control of your funds. The cost of crypto vs these systems is that it is WAYYYY slower, not scalable, more expensive in many cases, and requires the use of a massive network that consumes stupid amounts of energy even when it is less than 1% of the size it would need to achieve the dream of replacing fiat currency. It's just not worth it.
You haven't answered the question. How do you determine the value of benefit of decentralisation? If the high costs are not justified, what's the fair cost?
Average Joe may not be valuing decentralisation too high, but it's a different story for WikiLeaks (and alike), who had all their bank accounts frozen, or for individuals/businesses from Cyprus (EU member state, not some Banana Republic), who had seen their money just taken away from them, or for citizens of shithole countries with high risk of hyperinflation - you get the gist.
Other than exchanging physical goods (incl. cash), cryptocurrencies are the only way to transfer value in trustless, censorship-free, borderless manner. How do you put a value on that to say whether costs are justified or too high?
As for speed/costs - cryptos are performing pretty good. Bitcoin seems slow compared to other cryptos, but txs are irreversible and settled in average of 10 mins - this is huge advantage over the traditional means. Credit card purchases are rather expensive (especially for small merchants), buyers' could think they're free, but they're not - merchants pay the fees (and pass the costs to the buyers via increased product price, which also reflect costs of fraudulent chargebacks).
I just made a purchase on Aliexpress, my first payment attempt failed for an unknown reason, tried different card - it went through. Now I only have to wait 1 day for them to verify my payment. Wow, how fast and convenient. I'd be happy to pay even $15 fee just to use BTC if they had such option.
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Wrong. You only need tokens for decentralised, trustless, anyone-can-participate blockchains. You can have 'private', tokenless blockchains run by authorised nodes.
Actually it is right and you pretty much just admitted it. A centralized and non-trustless blockchain like the one you are describing is
completely pointless. You are better off using a database, which would be WAY faster and WAY fewer computational resources.
Private blockchains don't require high computational power (mining hashpower) at all. If it's pointless then why the hell is Swift (and others) spending presumably a fortune to explore/implement blockchain tech? They don't know any better? You want to email them and educate them on the issue?