And if citizens don't have access to guns, they'll still be used in crimes.
The second amendment isn't about safety or preventing death, it's about the right of the individual versus the overall collective. Governments and systems break down, but what doesn't change is the individual's right to defend themselves. Whether or not you think it improves individual safety in practice is irrelevant, because it's not your call (nor even the government's) to make.
When was the last time that private gun ownership helped overcome a dangerous government?
Whatever the reason for the 2A, in practice, it has contributed to far more death than it prevented.