Its not an argument, it's just an assertion with nothing to back it up.
Anyway, if you do ban guns, you'll just end up with rampant knife crime like the UK. This has all been tried before and we know what works and what doesn't work already. Why not just do what actually works.
It's really hard to believe that people still write stuff online without doing some basic searching. But here we are...
Here's a couple links to illustrate how RAMPANT knife crime is in the UK:
[1] For the year ending September 2019, there were 221 homicides involving a knife or sharp instrument recorded by the police. This figure is for England and Wales only and it excludes data from Greater Manchester Police (GMP).
[2] Recorded knife crime rose by 7% from just above 41,000 in the year to June 2018 to just above 44,000 in the year to June 2019, knifepoint rapes, robberies and assaults logged by police continued to rise.
I think it's pretty clear that your "rampant" is off BY A LOT. Knife crime in the UK is definitely not something to dismiss but guns (and gun crime and gun accidents) in the US tromp pretty much every other crime statistic in the "modern, civilized" world.
Even if we assume that intentional kills will stay as-is and just switch to knives, it'll still be a net positive as accidental kills will be reduced: it's much harder to accidentally kill a bystander with a knife than a gun.
Its not an argument, it's just an assertion with nothing to back it up.
Anyway, if you do ban guns, you'll just end up with rampant knife crime like the UK. This has all been tried before and we know what works and what doesn't work already. Why not just do what actually works.