There were a lot of 4e fans who felt betrayed there was a new edition and weren't afraid to voice it. They made a lot of comments about doom and gloom and predictions of a failed edition. Heck, I've seen on a few forums (some more than others) where people said they would actively do what they could to ruin 5e. Not sure how that works, but whatever.
For the record, I don't think that behavior is exclusive to 4e fans, and I'm sure many 3e fans had the same reaction when 4e came out. Can't be as sure though, because I largely ignored such discussions because I still stuck with AD&D. And I'm not saying AD&D fans didn't also do the same thing when 3e came out, but it was probably a lot more muted because there wasn't as strong of an online community back in 1999 as there was in 2008 (4e) and 2012 (playtests of 5e).