Why do car drivers ride on high beam always, especially on difficult roads which are single lane?

I ride a bike and my helmet is brand new. I also have very high quality spectacles. They were cleaned using a micro fiber cloth, hence they were as clean as they can be. I was riding my bike in dark and I was riding through a village which had a good road, but it was single lane only. And it was not a straight road, it had curves and all. Imagine a road that goes through a village. My speed was max 50kmph. Every time a car driver came from the opposite side, all of them had high beams and every time I thought I will crash because I could not see ANYTHING for those few precious seconds. It literally blinded me. Just why??