In my experience, insistence on the title varies inversely with the rigor of the discipline.

I think mathematicians and physicists are often so bizarrely intelligent that we want to label them.

I have to admit there are degrees along the spectrum where I can see it being justified. Any of the hard sciences, engineering. Maybe even economics. Psychology? No

siggy47

He does! I mock him. He laughs, but deep down I think he hates me for it. 

Does he go by "Dr."? Most economists have the good sense to just go by their names, like normal people do.