Part of socialist angst may be due to class envy, but I believe most of it is based on the phobia of scarcity.
If you are a socialist, chances are you believe that there is only a limited amount of wealth in the world. People are impoverished only because rich capitalists are hoarding it.
You probably also believe that global natural resources are scarce, the world's water supply is drying up, and irreplaceable species are becoming extinct.
This irrational fear of scarcity is what drives the socialist advocacy for abortion of the unborn and euthanasia of the aged and infirm.