A man can be thwarted in two ways:

1. By nature, through storms, disease, pestilence, wild animals, etc. - or though the competitive actions of other beings in nature (including other individual) who, by their nature, seek the same thing(s) he does, and might obtain it first, or exclusively; and
2. By human agency, wherein some individuals impose their wills on other individuals through coercive rather than competitive methods.

Coercive behavior involves a trespass or usurpation of the property boundary of another. 

Competitive behavior, while it may result in an outcome that thwarts the desires of others, remains within the property boundaries of the responsible person.

When an individual is thwarted by nature or natural processes, the question of morality is not manifested.

A man may have worked hard to bring in a crop of wheat - only to be thwarted in his desires by grasshoppers or a drought.

We do not say that the grasshoppers or the drought are immoral, for we do not view them as human agencies; rather we view them as natural agencies operating in a competitive way with man, true to their natures.