NASA's been flying the little dickheads up since 1991, when the space shuttle Columbia launched a payload of 2,478 jellyfish polyps in containers filled with artificial seawater and assorted chemicals into orbit. They grew and bred, and by the time the mission ended, a cool 60,000 space jellyfish were orbiting Earth and absolutely not mutating into a vengeful hive-mind out to destroy everything that you (you, specifically) hold dear.
The driving force behind this mass meducide wasn't the director of NASA getting vengeance over the jellyfish which stung him on a vacation to Greece, forcing several of his subordinates to piss on his leg and leading to the discovery of a very particular and embarrassing fetish. Jellyfish are actually fairly similar to humans in how they recognize and react to gravity, and researchers wanted to find out how being born in space affects this sense by breeding a shit-ton of them in a microgravity environment. The answer was that it fucked them over big time. While space-jellies looked similar to their Earth counterparts, their motor abilities developed very differently, to the point where they weren't able to survive on Earth at all. When the space-grown jellies were brought back to Earth, the sudden introduction of gravity basically gave them 24/7 vertigo.
So now they have a reason to hate us and our planet.