I do not find your arguments convincing. Terrorism always finds a way for financing. It also happens today through banks instead of cash. There is no reason to think that terrorism would increase because of cryptocurrencies rising in use. As if terrorists currently see their evil plots thwarted because of a funding issue. 'Must attack but cannot due to lack of funds...'. I am mocking this point of course but all that terrorism takes is a determinated mind and keys to a vehicle. Money is not a hindrance for terrorism. Not now, not with cryptocurrencies. That does not mean that cryptocurrencies won't be used to finance some terroristic acts, but it won't lead to a notable increase. Lack of money is not the driver.

That brings me to the second point. Government revenues may be impacted by the rise of cryptocurrencies. That could mean that certain projects can no longer be funded. But war cannot be funded that easily either anymore, leading to less waste and more opportunity for the private market (individuals) to help those unable. There is more altruism than described in economic text books (who assume rational players; quod non). A 'richer' group of citizens also leads to more charity and an increasingly free economy with less government waste means more opportunity for more people to make a living.

On the third point, I fail to see the connection between losing funds due to user error and 'black coins'.

I appreciate your efforts in writing down your thoughts but I do not share your worries on 'dark coins'. It is my expectation that most people do not want to be associated with these coins anyway and rather stick to semi-transparent networks with a degree of centralisation (think of KYC compliant exchanges and payment processors). Only where repression is high, the use of black coins can be expected to increase.