Are we giving too little credit to the insects?
They've had many generations to evolve alongside all human false light sources. Insect generations are usually pretty short. Perhaps they just find it evolutionary useful to cluster around human sources of light. Presence of human food, liklihood of bumping into other insects of the same species, warmth, etc.
If human sources of light were interfering somehow, they've had hundreds or thousands of generations to breed out that proclivity.
You assume it is possible to breed out without harming other advantageous behaviors which might not be case.