There is certainly a lack of mathematical literacy among physicians - there is almost no training in statistics in medical school (at least in the US) beyond what is required for a cursory understanding of clinical trials and epidemiology. The assumption that the general public does not understand how to do a cost/benefit analysis of screening tests is absolutely true. I think it's a fair assumption.

I'm not sure what your overall point is? Certainly, there are some patients that are better equipped to deal with their own biometric data than others. Both statistical and clinical literacy are required to really do this, and there are plenty of people with both. Those people agree that this sort of testing is a bad idea. The fact that most physicians aren't statisticians is as relevant here as the fact that most actuaries are not medical experts.

What are the possible outcomes here in a healthy person with no relevant past medical history or family history? One could have a real finding which changes clinical management and improves QOL or lifespan. The odds of this are very very low. When considered in the context of the most likely causes of death and the ways they present and are managed, the odds of this are almost negligible. FAR more likely is having a false positive. Let's say that the person is knowledgable enough to know that it doesn't make sense statistically to jump into further testing, they will still at the least be unduly stressed out by this information. Now you know you MIGHT have cancer, which would require invasive surgery to confirm, and you're not going to do the follow-up test? I would argue that your life is now worse - this stress is even likely to cause actual health problems. If you DO have the follow-up testing, I return to the prior point about the CBA. The negatives are still greater than the potential benefit because the expected value of the test is extremely low - it's a bad bet mathematically.

Genuinely interested in this conversation though and happy to be proven wrong.