High risk people should be in jails, prisons, mental health facilities and / or under the care of a responsible person at all times.
Only "responsible" people should be able to buy alcohol by your logic. So should we limit how much a person can drink and if someone buys them a drink, should that buyer be charged with being a straw man purchaser?
As many people die in DUI accidents as do by firearms. Yet, all you have to do is provide proof of age and you can buy all the alcohol you want. So, how come society is not equally outraged by drunks? Shouldn't you have to have a license to drink? The booze the bartender sells might very well be to a guy that just got out of prison on a DUI charge that killed several people.
Can you defend your life with a can of beer? Can you use a can of beer to kill an animal and feed yourself?
I say when someone cannot be trusted to own a firearm, they are a danger under any circumstances. So contain the bad guys and leave our Rights alone.