[btilly]

There are clearly a lot of details that you have to get perfectly right. However getting them right is an engineering challenge, not a physics challenge, and engineering for safety is something we as a society tend to do pretty well. (As opposed to engineering for cost containment, which we as a society are often horrible at.)

If I saw Elon Musk standing up there with cost projections, I'd be optimistic that they were in the right ballpark. If I saw virtually anyone else there, for a project of this type, I'd be assuming that they missed order of magnitude cost issues.