Moving this here.
Before SpaceX, there has never been a rocket that reached orbit (orbital velocity) and survived re-entry to land. Let alone was launched to orbit and re-landed a second time. Or a third time!
The technology existed for decades. There was no point in doing it. There still is no point in doing it. If it can safely be repeated 10 times over, then it will make sense.
Musk invented nothing (except a really strange rocket-fueled "green" cult).
Space shuttle?
That flew again several times but was too costly in refurbishment.
If falcon 9 is cheap to refurbish as it appears that it is, why wouldn't two or three flights make it worth while? Why are 10 needed to make it make sense? One third payload, partially expendable, some refurbishment/inspection: 2 launches might be close to savings each launch, 3 launches should produce cost savings. Might need a lot of such launches to recoup the development costs, but I don't see why it can't work out as a good strategy with a maximum of 3 launches.
Just because only 3 reflights so far, doesn't mean 4th and more reflights are not possible. I am expecting next Starlink flight scheduled NET late September will be a 4th launch. If it isn't. I think concerns will then reasonably grow that they cannot get a 4th reflight.
Are you really saying that if 1 flight in 9 or less need an expendable format so SpaceX never has to fly one 10 times, that it isn't worth it.
The benefit to SpaceX is mainly having to develop only one rocket and having several configurations in which it can fly. Essentially rightsizing the rocket to the payload - less expensive launches for smaller payloads. Has meant they have got very large share of launch market despite developing relatively few rockets and variants.