All fiat currency is backed by blood and violence at some scale, it's meted out by court systems, police and military forces. The US happens to be the sole global superpower so the scale is larger for us, but we're actually a very well behaved superpower by historical standards. The "Imperialistic Global Army" has allowed countries who could never have traded globally due to lack of resources to industrialize. The US Navy keeps the trade lanes open for everyone, or at least it did. Whether that will be a thing going forward is an open question now that the Cold War mentality is fading and our troop deployments at historical lows. We might be going back to a truly imperialistic attitude of protecting US and allied trade lanes and letting everyone else build their own Navies if they want to protect their shipping (many countries couldn't do this even if they wanted). But Bitcoin wouldn't be a solution to that either.

As for moral purity, it's no secret that a significant (albeit unknowable) portion of Bitcoin's current value comes from illegal transactions concerning everything from human trafficking to drug sales to organized crime rackets. The ability to obfuscate financial transactions is part of its intrinsic value, so anyone with an interest in doing so will be attracted to it. Plus if Bitcoin were to somehow grow large enough to even consider replacing the dollar, all the blood behind the dollar would simply shift to Bitcoin in some (albeit likely different) manner. Someone has to enforce monetary policy and financial laws, a chaotic, decentralized enforcement would arguably be even worse than centralized fiat enforcement.

There's no way forward financially without some blood on your hands at some stage. So for my money I'm going to build my financial house on solid ground. I'm all for making the system more just and less bloody, but IMO Bitcoin isn't it. In the meantime we've all got to play the hand we're dealt, the only other option is to be a martyr, and while they might get some occasional press and lip service, martyrs typically don't accomplish much.