Bitcoin is actually pretty unfriendly to terrorist groups because it's a public ledger, making it relatively easy for law enforcement to track. By contrast, being backed by a government doesn't actually make, say, the dollar immune to nefarious uses.
Value is in the eye of the beholder. If Bitcoins sell for $38k then they're worth $38k... right now. As the payment network related to Bitcoin spreads wider, its utility goes up, and the value to holders increases. This is similar to how a fiat currency's value largely comes from the ability / obligation to pay taxes in that currency, but rather than being created by governmental mandate, it is developing organically, bootstrapping.
If the Internet had had a payment system built into it from the beginning, spam may never have become a problem. Advertising would not have been the only effective way to monetize. And so on. Getting to a micropayments world with the Lightning Network or whatever comes after it is a technological revolution that will likely have wide-ranging consequences.
Some of my reasons.