It’s basic economics and smart business I think. They charge ridiculously high fees because people will pay it out of FOMO. The average person that just heard of bitcoin last week wants in no matter the amount. They also probably haven’t found the cheapest or most efficient way of obtaining btc.
You make a valid point about if someone were to lower the fees they could grab a significant piece of the pie but there again is that fine line of how much can I charge and how much will they pay.