Also, what makes the Democrats think that rioting, breaking windows, destruction of property, threatening to kidnap Republican delegates, makes them look good?
No one's addressed this part of your post yet.
I've commented on part of this before, although the discussion is more like "how can a party that champions the ideals of freedom and tolerance so quickly trounce on those they don't agree with?". And that's because they have a kind of myopia I still don't understand, even though I've observed its symptoms.
Consider two situations almost exactly the same - a liberal professor calling occupants and workers in the twin towers "little Eichmanns" - Ward Churchill - and a Harvard president daring to mention that the brains of women and men are wired differently thus possibly contributing to their lower numbers in the sciences and engineering (Larry Summers).
Liberals were able to force Summers to resign, because those kinds of comments were intolerable. Churchill, however, was hugely supported as being able to make objectionable remarks because, well, that's how free speech works. (He's since lost his position due to other circumstances). When this was in the news, Pat Sajak wrote an interesting piece on the differences. You can look it up if you want.
But basically - there's no political "spectrum" to these far left types. They believe they represent the mainstream's view. They are not "extreme" in their own eyes. There is simply their own "mainstream" view, and those of the "extremists" - the so-called "right-wing". They just don't see a spectrum of far left, left, center left, middle and so on. There's just their view, and the nut cases they disagree with.
It would be as though you had a forum of scientists, and a portion of them believed in a flat earth. You wouldn't give them equal billing or equal time for their views - because they're patently absurd. You don't balance science curriculum with phlogiston theory and the "aether". It's just false.
Some of these violent types feel "threatened" by the right. To them, it's as though skinheads and Nazis were actually gaining power in the United States. They don't feel the need to "prove" their ideas in the realm of public opinion. They just have to stop it.
I don't UNDERSTAND it, but my observations are, this is how it works.