I think an important angle of "consider the cost" is that materials in R&D are pretty much ALWAYS cheaper than a team and time. For example here if the whole rocket was a 4mm thick 9m X 118m cylinder, the actual stainless steel would be like $700K [1]. While the rough headcount ceiling cost at SpaceX (7000 employees) is around $5M per day. And this way they get actual valuable engineering experience out of it, rather than just arguing in conference rooms like a more conservative company would have done. I think fail-fast prototypes are super valuable and are what good R&D looks like.

[1] https://www.wolframalpha.com/input/?i=%28pi+*+9m+*+4mm+*+118...