The New York Times has made one of the better arguments for Bitcoin that I've seen this year. This article openly discusses the aspects of mass shooters purchasing weapons using credit cards, and how law enforcement is advocating for intervention on the part of payment processors. Regardless of how anyone here feels about firearms, I feel we can agree that people should be free to spend their money on any amount of product provided they are not breaking the law.
The result of course is a call for banks to either outright prevent purchasing firearms using credit cards (which may include debit) or report such purchases to the government or law enforcement for follow up. In either case, provided the purchaser is engaging in legal action, this would constitute a law enforcement response akin to The Minority Report. Purchase too much, and the police may be at your door asking questions.
Bitcoin's power via a permission-less system guarantees that people are able to spend their money with whoever they desire without needing the permission of centralized payment processors like Visa, or the permission of banks like Chase. While the subject of firearms is certainly controversial, it is naive to believe such scrutiny would be limited in this area. If the government and the public begin holding banks responsible for every come committed made possible by their banking services, banks will readily turn over any information to avoid regulations.
This is what we all fight for with our Bitcoin support. Bitcoin provides the best case for liberty when it comes to the free exchange of goods and services. We are facing down a future by which central banks will collude with government to spy on citizens and punish behavior that is perfectly legal, but only because it isn't deemed "normal". The level of freedom that Bitcoin can provide is likely more than we could possibly imagine.