The Q themselves are counter to that opinion. Look at all of the Q we've met between TNG and even Voyager. They're not often presented as the most stable, mature, or centered lot.
Don't humans likewise counter that opinion? Do any "lower" lifeforms prey on their own kind through bullying, mockery, or outright violence like humans do? Do animals like to torture, experiment on, or "pull the wings off of" other animals simply for pleasure?
Seems like the more advanced the lifeform the greater the tendency to test, harass, mistreat, torture, manipulate or otherwise mistreat lesser species.
the answer to your top question is a definite yes. You ever see a cat toy with a mouse? Killer whales will also "play" with their prey sadistically before eating sometimes. Monkeys and apes also can be vicious toward their own kind within their social structures.
You think Humans are worse because you read stories in the news everyday about what they do, and you don't read about animals behaving viciously.
Sorry to disappoint you but things are no better out in nature.