Every country is special. The point is, social welfare works in reducing crime in Korea, it helps in reducing crime in Denmark. It helps in radically different cultures and in countries with totally different histories. It works because the majority of crime is driven by desperate people that just don't exist if they have basic social welfare.
The mechanics can be complicated, but the basic principle is simple: there are no states with a decent safety net that have US-level crime statistics.
PS: You do realise you don't need all those weapons, right? The US is bordered by Canada, and Mexico. Nobody is ever going to invade. The historical normal of the US is to have basically no army, and it worked just fine. Nobody has even seriously considered invading the US since the British left, despite two world wars, because it's obviously so impractical.
The mechanics can be complicated, but the basic principle is simple: there are no states with a decent safety net that have US-level crime statistics.
PS: You do realise you don't need all those weapons, right? The US is bordered by Canada, and Mexico. Nobody is ever going to invade. The historical normal of the US is to have basically no army, and it worked just fine. Nobody has even seriously considered invading the US since the British left, despite two world wars, because it's obviously so impractical.