Don't feel guilty at all, its just business.
2 primary reasons are :-
1. People from other countries pay better then the local markets, or rather exporters can charge a lot when shipping to other countries.
2. It happens in the US as well, where native species are overlooked and imported species are fancied. Its the same here as well. Hobbyists are getting more and more interested in natives, but native barbs and Danios, Badis varieties, catfish varieties,etc. are an easier purchase from the hobbyists' perspective, than snakeheads.
I am in the central region of the country, most of the snakeheads that are found in the country are from the north eastern regions.