I've been pondering a lot about this phenomenon (the Big Important Job). Thinking about how your husband needs constant validation and his claims that his co-workers heap praise upon him (and how my own husband was very happy with the praise of his team and disappointed to get no praise from his boss).
Then I remembered that my husband's "mid-life crisis" started when he was accidentally sent an email which contained a frank account of his shortcomings in the job. It was like he went into shock for a while (cold, jittery, unable to process), but the experience has been positive overall, as he was willing to look at the facts squarely and admit that those shortcomings are real (of course there is a lot he does very well, but inevitably things he is not good at). He ended up deciding to take a change into a role that suits his strengths instead of constantly battling to be somebody he's not.
Your description of your husband seeming panicked, "against the odds" etc made me think of now mine looked when he was faced with his own inadequacy. It took my husband's boss's frank appraisal (which was only shared by accident) to shake him up, and change from thinking "I need to succeed at all costs" to realising "I won't succeed at this, but there are other things I can succeed at". Your husband IS the boss, so where could this appraisal come from, for him? Does he have a mentor or mentor-type figure that he might listen to?
No solutions for you OP, but I hope that our experience might help as you understand / navigate this.
Your husband talks about his "journey" (mine had started to speak like this too - the whole company do) which is cringey, but it's a good way to think about life in general. This is only a section of your life together, and it does not have to last for all of it - you can get through it, and out to another phase where work is not the be-all-and-end-all of his existence. However, it could take a seismic event to get him to change, as this kind of thinking is like a rut that is hard to get out of.