This is tough for me, because some of your points are great and some are very wrong. I suppose I'll just have to go down the list:
"1) Environmentally damaging": Yes, very much this.
"2) Unstable": Correct and important.
"3) No sensible control of supply, the "Mining" is the stupidest part.": Incorrect. The supply control is built into the specification of the currency in the first place. There is a finite number of Bitcoins that can ever exist, for example. Most proof of work ones have difficulty levels which act to restrict supply. This is one of the things the designers intended right at the start.
"4) Transactions don't scale.": Probably the most important point you brought up and one I've had to explain to cryptocurrency fans for years.
"5) Transactions are 1000s of times more costly in time and computers and energy than IBAN.": Yes, this too, although it's kind of a necessary corelary to 1 and 4.
"6) The only reason for Blockchain is to decentralise, have no control and enable a degree of anonymity. All naive and stupid design decisions.": Why are those naive or stupid? The users don't trust central control, so they remove it. They also value privacy. I can see not caring about those yourself, but is there a reason it's stupid for others to care about them? I'm not an adherent of cryptocurrencies and yet I think those points have value.
"7) It looks like a Pyramid scam": Other than having a central controller, using others' money to pay back previous investors, or the person who is going to walk off with the money. It's missing most aspects of a classic pyramid scam. You can scam with it, and it's a very risky investment, but it is not nor does it look like a pyramid.
"8) It is purely speculative in value.": A lot of things are speculative in value. Avoid investment, if you will, but many others don't view this as a deadly fault.
"9) Not actually a currency.": Not a good currency by any means, but you can have it and pay people with it, it is fungible and can be exchanged. Functions like a currency.