system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: How did we make plastic that isn't biodegradable and is so bad for the planet, out of materials only found on Earth?

I just wondered how we made these sorts of things when everything on Earth works together and naturally decomposes.
gpt
Plastics are made from organic materials, oil, which is hydrocarbons that were once plants, so one might expect plastics could decompose as quick as any plants, except they don't. The reason is that there's very little life on earth that knows what to do with the molecules that makes up plastic, humans mix other chemicals with the hydrocarbons to make new molecules that never existed in nature before, they're so new to biology that almost nothing exists that can munch on it and use it to grow. The chemical bonds in plastics are tougher and weirder than anything natural, which is what makes them so useful to us but so awful for nature. There are some bacteria that can break down plastic with enzymes, because 'life finds a way' and hopefully research in developing that into a commercially viable process will make plastic recycling something we can actually do at scale.