If we allow the extremely wealthy to have an extreme advantage in campaigns, we'll end up with a government that only serves their interests. Why would we expect anything else?
The solution to this is public funding of elections that puts all candidates on an equal playing field, or at least overturning Citizens United and only allowing direct donations under the maximum including from yourself.
Hiring dedicated trolls at $2500 a month, you mean? Do you have a source for that?
I don't think it's antidemocratic. Bernie Sanders is doing just fine with a fraction of the ad spending. Ultimately, nobody is being forced to vote for him. Super Tuesday will be the first test, and it's very possible that Bernie will sweep all of the big states himself.
No - it's not that he's spending his own money. But rather, how he's spending it.
And they're not "upset". They're calmly pointing out the obvious: that this kind of attempted influence buying is profoundly dystopian and antidemocratic.