Refer back to where I said this.

Getting caught with a gun carries jail time to whatever is needed to persuade the public that it isn't worth owning a gun. (Minimum 1 year, goes up depending on threat of gun and amount, but it would need to be more than just a fine.) That's just an example though. More qualified people would decide that.

Most normal people aren't interested in going to jail and would take a sum of money instead. People have careers, families, and for the most part wouldn't be willing to ruin it over a gun. It wouldn't go away overnight obviously, but over time it will. There would be acts of terrorism for a short while, but it wouldn't last too long. That isn't what's stopping it though...

The current problem that stands in the way of this would be that half of the government wouldn't enforce it / possibly fight back. If you live in a Republican controlled area, you wouldn't be worried about getting locked up for it because they wouldn't enforce such a thing. It isn't possible currently, as of 4/18/21. This would require an event, many multiple events, to change their minds but you're correct that it wouldn't work today.