Almost everybody I’ve ever seen who insists on being referred to as Doctor and who at every possible opportunity refers to themselves as Doctor who is not an MD is usually insufferable.
Many of them are educators who are often little tyrants.
It's like in Karate. To consider someone to be your teacher (Sensei) is a very important thing. A Sensei teaches much more then kicking, punching and forms. I have a Sensei who has been a guide in life for over 40 years. He has earned other titles in that time. But in our relationship calling him Sensei is the highest form of respect. In the USA, Karate people love their fancy titles. They glom on to Japanese titles that have long since lost their original meaning. They demand to be called by those titles and are insulted if you just call them Sensei. I am not sure about the rest of the world, but like those fancy Japanese titles, “Doctor” is a much abused title in the United States.