The main issue is about control. We can certainly see how the government is encroaching upon more and more aspects of our personal lives and creating new rules and regulations almost daily. They can only go so far so fast when a good chunk of the population is armed. By "they" I mean many top government officials as well as certain people behind the scenes with a great deal of money. George Soros comes to mind.
Basically there are two types of antis. The first type is the type that truly believes gun control with make this world safer and "protect the children". They have probably never fired a weapon and feel very uncomfortable around them. The swallow what the media tells them hook, line, and sinker. These people can be professors, elementary school teachers, or really just the neighbor across the street.
Then there are the guys at the top who actually pass these laws and they aren't doing it for the children. They aren't afraid of guns and most own them for protection or recreation. They just don't want "us", to have them. They know gun control doesn't reduce crime, the know all the stats and only want to eliminate guns because they stand in the way of their agendas.
And then there is Feinstein who is just crazy.
That's an oversimplified answer but my point is that some people are genuinly convinced that firearms are dangerous to SOCIETY, while others are convinced firearms are dangerous to THEM.