: 1. Environmentalists.
: These people are considered quite dangerous and are sometimes referred to as "kooks". They are "kooks" because they talk about "issues" and "values" that are often outside the domain of the PMM. And since All of man's desires can be addressed by the PMM, (it being the very fuel that runs the engine), many free-marketers feel that such environmental concerns are a: irrational; b: paranoid; c: delusional ravings of tree-hugging nut-cakes.
Just in case some folks missed something:
"The function of American socialism (and its leafy subsidiary, environmentalism) is to provide something to spend money on, filling the coffers of the very class socialists claim to despise. Marx must be spinning in his grave so fast he could be wired to generate electricity." --L. Neil Smith