Advertising on Reddit is not the same as advertising in general.
If you advertise on Reddit, you're advertising to a violently anti-corporate anti-advertising audience, who may love you, but very well may hate you. You could be subject to a witch hunt at the drop of a hat.
I very much doubt advertisers would be lining up to advertise to that crowd. They're hardly big spenders either.
This is an unsubstantiated claim. Some of reddit's communities are like this, but most are not. If you're just viewing the front page, you are viewing the lowest common denominator, which could give you this impression. But reddit is a very heterogenuous community.