That construction has always bothered me.
People will say it's because you envy a person not a thing, and that on the surface is okay, but then why isn't it I envy you for your thing, or because of your thing?
Why is it okay, in this particular construction, to drop the preposition? It reminds me of the french "Once upon a time" construction: Il était une fois une vache qui rit. which also seems like it's missing something.
On the other hand there are also examples on the internet that do include a preposition. For example:
and this makes it more confusing because now it seems like it's more of a personal choice and I wonder even more why they are both allowed and which came first?
Best Answer
Envy is a member of a Levin class. Beth Levin's book English Verb Classes and Alternations: A Preliminary Investigation (1993 U Chicago Press) is a classic and is very useful for anyone interested in English. (from the online Verb Index of the book)
This class of verbs denotes positive and negative psychological states of the experiencer subject, and participates in three major "Possessor-Attribute Factoring Alternations", as Levin calls them (examples below from Levin pp 72-6, illustrated with envy):
1. (2.13.1) Possessor Object Alternation
They envied the volunteers' dedication
They envied the volunteers for their dedication.
2. (2.13.2) Attribute Object Alternation
They envied the volunteers' dedication
They envied the dedication in the volunteers.
3. (2.13.3) Possessor and Attribute Alternation
They envied the volunteers' dedication
They envied the volunteers their dedication.