Track days, what he said.....
I had radar detectors from 1978 until 1990. When the instant-on became prevalent I sold off my last one.
Main reason is that if you get stopped with one, 99% of the time you are going to get a ticket. I LOVE the guys who pass me on the Mass Pike with one sitting on their dash, or anyone else moving fast: I refer to them
as my "radar detector."