I have been to many comps and I usually talk/sit with the fastest people who are there. This never happens. It's always an encouraging atmosphere, even between the big rivals at big comps. This is such a strange idea, it actually feels ridiculous to me.
On topic: When I first found Speedsolving I felt, as you do, like everything posted here was negative. When you get to know the people here, you realize they are not usually being mean. If someone is being mean they are usually called out for it. What you take to be rudeness is often a more experienced member correcting a less experienced one. After a while of reading this forum (I haven't been on for long at all, but I have lurked for years) you get tired of new members asking the same questions that could easily be answered with 1 simple search. People want to be spoon-fed information. More experienced members usually just tell them to figure it out themselves. It's not mean, just teaching them a lesson.