The root post's comparison was to someone beside you at the supermarket, rather than "sniper at a distance". The capacity to kill is almost universally distributed, it's just that the vast majority of us are not murderers.
But sure, it's actually one of the justifications for the 2nd amendment. Firearms really are sort of an equalizer, and do more equally distribute the risk to even the most powerful.
With guns, it's literally just a button push kind of UI. That this is controversial is just insane to me. Every 2A nut knows that guns are effective killing machines, that's why they like guns. Yet we end up in these threads anyway watching people try to deny it.
No, it doesn't, not in the context we're talking about. A quick Google says per capita knife deaths in the UK are 4.9/Mpop, gun deaths in the US are one hundred thirty seven per million.
Europe should absolutely solve the "knife problem", sure. But even eliminating it entirely would equate to like a 3% reduction in US deaths. Arguing, as you seem to be, that the US should do nothing because Europe has a comparatively tiny problem seems poorly grounded.
Widespread gun ownership invariably makes the problem much, much, worse.