There are a couple of ways to look at it:
1. If another player(s) are able to start and freely operate as a competitor then talented engineers will have more options for employment and each entity will have to compete on both price AND quality in order to win business. This requires continued investments.
2. If the original player is able to use regulatory frameworks, lobbying and other tactics to enforce a monopoly, then the state has a duty to break them up to ensure competition.
Option 1 is more free market where the problem solves itself. Option 2 involves use of the government to both create and resolve the problem.
I don’t personally take issue with either because the solution is still competition. Whether Lockheed, SpaceX, a Boeing breakup or some company we haven’t heard of gives it to us isn’t a big concern. We just need competition.