#2 He felt WWE intentionally buried him with the exchange with Nia Jax
After Nia Jax's appearance in the Men's Royal Rumble match, she confronted Dean Ambrose on an episode of Monday Night Raw. Jax went on to throw him out of the ring, and nothing came out of the feud as weeks passed.
In a backstage meeting, Ambrose had told Triple H and Vince that he was leaving, and the segment was immediately planned for him. He felt that this was WWE punishing him for deciding to leave the company.
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Months later, The Revival rejected a lucrative contract and were soon put in an angle where Dash Wilder was seen shaving Scott Dawson's back. Incidents like this one give weight to Ambrose' claim that the segment with Nia was, in fact, a way to get back at him.
A better idea for Vince would have been to sit down with Ambrose and try to convince him to stay, by offering him a bunch of perks and a push to the main event scene. The segment with Nia was completely unnecessary, looking at how it didn't go anywhere past that one night.