When was the last time you complained? Yesterday? Last week? An hour ago perhaps?
When you complain, can you recall any good thing it benefited you? Did it ever make you feel better? Short term, long term? Did complaining solve your problems? Did it help get what you wanted?
Why do you complain? Because your expectations weren't met? Because you feel like you're immersed in a situation that your parents and friends don't approve of? Because things don't work the way you would've wanted it to?
Frustrations, issues, concerns, problems... whatever you call them they will always be there. It is every person's responsibility to take appropriate actions and resolve it. The efficiency of the motion to resolve it however depends on the approach. It's not really wrong to complain... but it is wrong to deal an issue with anger.
Things can easily fall apart when you start entertaining the thought that things should be perfect. Nothing is perfect so don't complain.
Trust me I complain a lot before. It sucks.