Absolutely, I do believe that SpaceX going public will largely be the death of that company. And, depending on when this happens, it could even herald the second death of space in America. The one thing that's good here is that Elon has stated that he will not be taking SpaceX public until transit between Earth and Mars is well established.

The point I'd make is that leadership really matters. Boeing, at its peak, almost certainly had orders of magnitude more talent than SpaceX did in its early years - in no small part because of what you mentioned. And they absolutely had many orders of magnitude more money and access to funding. But their leadership was just absolutely abysmal, and consequently the potential of that talent was left completely untapped.

But on the other hand, like you mentioned there are incentive problems. Even though Boeing failed to tap into their potential, their stock price has been constantly and steadily going up for decades. Even their planes literally falling out of the skies was but a brief stumble, the damage there largely repaired owing to the start of a profitable new war. So in this regard I doubt their leadership is particularly disappointed with their results. They achieved what they set out to do after all. And that's pretty disappointing.