Yes, it is a terrible idea for terrorists.

And currently, bitcoin is too hard to use for terrorists or most criminals. You have to be relatively sophisticated. Yah, you may have gotten your grandma a wallet, but that's not the same as mastering the level of opsec to fund a clandestine organization using cryptocurrencies...

And further, since every transaction is recorded forever in the blockchain if any future address is compromised, the entire network can be compromised instantaneously....

Bitcoin is really worse for terrorist financing than good old USD.

And we "lost" trillions of USD on Pallets in the Iraq and Afghanistan wars.

Good digital currency will be useful to terrorists just as a good internet is. But just as the internet creates a more connected and prosperous world that reduces conflict and terrorism overall, so will digital currency.

Also, it reduces the threats posed by governments against their own people. Government repression, like that seen in Venezuela or for a more extreme example, North Korea, can kill far more people than non-state terrorism, and tools that empower individuals help resist that.

I have no idea. But it's a great way to get relatively anonymous donations. At least, if you educate your donors to mix first. Also, properly mixed Bitcoin is great for anonymously leasing VPN services and servers, and for buying fake Facebook etc accounts, which are all useful for advocacy. And maybe black-market arms dealers accept Bitcoin now.

It has been used for ransoming such as HBO's case.

It’s it about bitcoin as Monero wouldn’t be a terrible idea though, another digital currency

But attempting financial sanctions as a way to deter use? That will be a waste of everyone’s time and money

One idea is if digital currencies get big enough then it will accelerate the insolvency of the state from its obligatory attempts to curb use. Far fetched now, less far fetched than a year ago