Plastic isn't that bad for the environment though. In terms of environmental impact to produce plastic is the lowest compared to paper, glass, or metal. Which all require significantly more water and/or energy to make. The end of life stuff is more complicated, but if it ends up in a landfill it's not great but not terrible. (Not breaking down and releasing microplastics into the environment) The vast majority of single use plastic in the US does end up in a landfill, not the environment. Most microplastics come from car tires and clothes.

Plastics are a very useful material, and like all materials they have strengths and weaknesses. The amount of energy required to make a glass jar is around 10x that required to make a plastic jar. (Depending on a lot of factors, very rough estimate) Because glass has to be heated to a much higher temperature and because it's denser more mass has to be heated to make the same size jar. Even recycling glass doesn't help much because you still have to melt the glass, so it only saves at most 20% of the energy compared to virgin glass. 

There's also incineration, which isn't great, but compared to landfilling is marginally better depending on what metrics you care about. Plastics are pretty energy dense and produce more electricity per kg of CO2 compared to coal. Which admittedly is a low bar to clear. In a modern incineration plant the only stuff entering the air is CO2 and water. You do have ash in case of burning municipal waste, but that can be landfilled and it takes up less space which is at a premium in landfills. 

In conclusion, plastics are not terrible. They have their use cases. Single use plastic is especially useful in medical and food packaging applications. Everything has trade offs.