I'm sure you'd also like to see gangbangers deprieved of semi-automatic weapons. What would you do to reach that goal? Pass a law making them illegal, so law-abiding citizens won't have them but criminals, who buy guns illegally on the black market, will? Or would it make more sense to allow law-abiding citizens to defend themselves, and have severe punishments for anyone who commits a violent crime? Would you like your gun confiscated simply because a criminal used a similar gun to commit a crime?
Think about this logic for semi-automatics, and then apply it to automatics. It works the same way.
Well, who wouldn't like to see gangbangers unable to get weapons of any sort, because they're not the ones who will use them responsibly. That's not the issue.
Look at the homicides in Nuevo Laredo, Mexico, where the gangbangers have automatic weapons. Better have lots of life insurance if you're the chief of police there, because the odds are good you'll die in a fusilade of bullets from an automatic weapon while driving to work.
MS-13 is active in our cities. Would you feel safer if they had easy access to machine guns? There's really no pressing valid reason for any law-abiding citizen to have the capability to mow down 30 people in a minute, is there?