We discuss the environmental impact of antkeeping often and some people worry that collecting queens could harm ant populations.
The consensus seems to be that, unless antkeeping becomes much much much more popular attracting industrial levels of collecting, taking alate queens is probably the least harmful way to get an ant colony.
Queens are released in the 100s and most are eaten by birds, or never find a place to nest. A queen collector denies a bird or lizard a meal mostly.