First past the post is plutocratic

We can see that democracy is good for the poor because it enables property rights to be determined not only by wealth but also popular opinion. The very rich are threatened by democracy because it means that in theory their wealth can be appropriated by the state, so true democracy is a threat to the rich. If there is a first-past-the-post system then the people do not have true democracy and the very rich are able to retain their wealth.

First-past-the-post is against democracy because it doesn't let the people take power from the establishment and this serves the rich. True democracy would enable the people to redress perceived economic injustices but the presence of the fptp system prevents this and makes sure that the rich retain their wealth.