Gun buybacks sound plausible enough. You offer people money in exchange for their guns and you get those guns off the streets. If you knew nothing else about guns, crime, or anything like that, it would make perfect sense.
However, the more you know about those topics, the less sense they make.
While people often turn in guns at buybacks, many people game the system. They use them to dispose of non-functional firearms or even dispose of crime guns they don’t want associated with them. Some people have even manufactured fake guns for a few dollars, then took the buyback money and used it to buy a real gun.