Plastics are incredibly useful. Tons upon tons of bottles end up in landfills, oceans, etc. Even with plastic recycling, PET yields aren't 100%. There is only so much oil and eventually the plastics we have will cease to be recyclable.

I'm not trying to say that it's wrong to use a disposable plastic bottle from time to time. There's not anything wrong with having a case of water. But no one with access to clean water should primarily use disposable bottles. It's lazy and shortsighted.