Well, hindsight is 20/20, but I think he and Meghan would've gone a lot more quietly and not been filled with outrage and a desire to hit back if some kind of compromise could've been reached, rather than just saying 'No' to everything they wanted.
Harry clearly feels that Charles, William and senior courtiers ganged up against him and I think much of the hatred and bile that he and Meghan have directed against the RF since is due to the sense of injustice they felt at basically being told 'Sure, you can leave, but you're on your own'.
Maybe I'm wrong, but his insistence in the Tom Bradby interview in Jan that he STILL thinks that the half-in, half-out model could work, seems to confirm that he's still sore about being denied it. It was, after all, their exit plan and it was blown out of the water, so all the shit they've done since then is them scrambling around and trying to find a way to support themselves and their fancy new lifestyle without their royal status, money and any kind of practical support. And it hasn't been good for them, or for the RF. Keep your friends close and your enemies closer and all that.