Any artist with an intense passion for creating, might come across as greedy and delusional. One has to try and understand that being a performer in a rock and roll band is no different than any other business venture. Without any amount of stubbornness and/or passion about the work, the chance of success is minimal.
However, it's not merely the financial aspect that drives an artist. Rather, it's something that is a little more hard to explain to a person who isn't an artist themselves. Most successful artists, or any successful business owner for that matter, possess a certain "Fire" that burns inside them. Sort of like an itch that needs a scratch and one that never goes away.
Henley and Frey, IMO, were simply great leaders who shared that "itch".
Creativity, thoughts and ideas build up within a person over time and begin to boil like water in a kettle and like Glen said in the documentary, "If I don't make music, I'll go nuts!". I'm paraphrasing here. With that said, I found Glen and Don to be truly inspiring.

Its a really long storybut I tend to blame Henley and Frey for being greedy and delusional.

And maybe a little jealousy too, Chas
After all, Felder has a great voice and is probably a virtuoso on guitar compared to Henley.

After watching the Eagles documentary, I believe Don Henley was fearful of Felder overshadowing him if Felder was allowed to sing as he wanted.
Paranoid delusion.

After watching the Eagles documentary, I believe Don Henley was fearful of Felder overshadowing him if Felder was allowed to sing as he wanted.
IMO, Felder has a nice voice, which even sounds a little like Henley's.
Too many "cooks in the kitchen", that sorta thing and with Henley and Frey being as stubbornly as they were on their "vision quest", Felder never had a chance.
However, he made up for it with this tune:

Classy.

He was kicked out Even though he's responsible for "Hotel California" and totally expanding that band into many genres. Also, he's by far their best guitar player.
No Bernie, no Randy either.. they were founding members, they deserve at least a mention