I have three friends that tend to complain about everything. One of them I really like and while he does complain, it tends to be about things that genuinely bother him. He's a little neurotic and he's a pessimist, but it's part of his charm somehow. I feel like we have real conversations and not just one-way whining sessions.
The other two I kind of wish I weren't friends with because they have gotten so annoying. Both make tons more money than me and lead very privileged lives (healthy, wealthy, successful, intelligent, talented, highly-educated, etc.). They seem to have or be able to get anything they want in life. Yet I can't spend time with either of them without them talking my ear off with endless complaints and negativity. One of them is almost impossible to drag into a positive conversation, even if you try to ask him about his favorite things (music, beer, baseball, etc.). The other complains all the time but brags endlessly, so it's like he wants you to think his life is amazing and yet won't stop complaining. Quite a combination.