Admittedly this straddles between personal and professional.
Reasons for disrespect: makes unfounded, speculative, assumptive statements without realizing the difference between fact and conjecture; projects magical thinking; is fundamentally narcissistic; had overwhelming need for admiration or idolizing; explains away mistakes; employs subtle or less subtle manipulation to gain social dominance, and is certain in opinion or about the unprovable.

I've seen all these traits in a couple of therapists I know outside of their practices. They're two of the most attention seeking human beings I've ever met.