I don't understand the arguments against gun control
The important bit is the fact that reputable studies by various agencies, including the U.S. government, have found that there is no correlation between gun control and homicide rates. There's also the argument that "When guns are outlawed, only outlaws will have guns".. because criminals don't care about the law, and guns are easy enough to make in a machine shop if there aren't already hundreds of millions of them already in circulation like there are in the United States. This is already obvious when you look at Washington D.C. and Chicago, two cities with extremely strict firearm laws, yet also very high firearm homicide rates. Criminals will arm themselves regardless of the law, and strict gun control laws leave law-abiding citizens unable to defend themselves from armed criminals. Case in point: Mexico and Brazil, two countries where guns are almost totally inaccessible to those who follow the law, and ubiquitous among those who do not.
Other countries may have different situations, but there is no clear pattern that gun control is actually effective at reducing crime.
Also, in the United States, there's that pesky Second Amendment to the Constitution that a lot of people take very seriously, and for good reason.
Oh, and the fact that every year, there are between about 145,000 and 2.5 million (depends entirely on whose statistics you believe) incidents where law-abiding citizens defend themselves from criminals with firearms in the United States. The vast majority of the time, it ends without a shot being fired because the assailant flees when the would-be victim pulls a gun. Even the lowball figure of 145,000 crimes prevented is a very significant one.