I can understand how a lot of these former players think it's so easy though.
You have some guys like Mark Jackson, Avery Johnson, Larry Bird given jobs right away, and so everybody thinks it's that easy and a job should just be given to them.
The thing is, every NBA player has been auditioning for this role their entire pro playing careers, but they don't even realize it.
Are you good with the press? Did you have good relationships with coaching, management, and all the other staff? Did you demonstrate leadership during your career? Did you mentor young players when you were a vet? Do you have a great basketball mind and a love for the game? Or do you just happen to have the physical skill set for basketball and that's why you made the NBA, didn't care about anyone but yourself, weren't easy to coach, didn't cooperate with the team staff, etc?
I think you get a guy like Mark Jackson, most likely always demonstrated that he loved the game, had a great basketball mind, showed leadership, and was always great with the staff, so ya he get's a job no problem.
But then you have guys like Dee Brown and Walter McCarty, maybe they love the game, and were good with the staff and press, but they never demonstrated leadership or a great basketball mind (maybe they only had average-to-good basketball minds). So ya they have to work for it a little bit. Brown had to start in the WNBA, then D-League, and now is finally an NBA assistant. McCarty had to start as an assistant in college, then worked his way up to NBA assistant.
Then you have guys like Kareem, Parish, and Ewing. Maybe they only showed they were tall and good at basketball, but never great with team staff or the press, and never showed a great basketball mind? That's why they struggled to get an NBA coaching job. (Ewing seemed like he expected a coaching job right away, wanting to be a head coach of the Knicks with no experience, then realized he had to work for a coaching job and show he had what it took since he didn't show it during his pro career, that's why he has a job now).
So ya you have guys like Parish who 15 years after they stopped playing, now decide they want a job (for the wrong reasons), while demonstrating zero desire or ability to coach during a long NBA career, and doesn't understand why they aren't just handed a cushy job. You had a 20 year career to show you would be a good coach, what was going on then?
(Obviously I'm assuming some things here about players personalities and behind-the-scenes behavior, but I think that's generally how it goes down).