Bitcoins can only be as evil as cars, guns, LEDs, pin-and-tumbler locks, trusted computers, square-rigged ships, Jacquard looms, and enriched uranium. The point is that these are technologies, not people.
But can technology be immoral? I'm a bit rusty on all that stuff but it sounds like we're talking about two (subtly) different questions. I would argue that technology can be used for evil, but technology just sitting there by itself is no more evil than rocks or sand.
If you can prove that a certain technology can not or will not be used for good, then that raises different questions.
It's pretty clear that the hydrogen bomb is, in the sense you give, "immoral".
Sure, you can come up with complex, hypothetical scenarios where it has value, but fundamentally it has but one purpose, which is to murder millions of people.
In most moral systems, murder of one person is immoral, never mind millions.
