Personalized medicine is great if you want to charge people a lot of money for marginal results, or if you are in the sciences and your goal is full understanding of everything in human biochemistry.

But all the real, meaningful goals in medicine are basically the same for everyone, barring the very, very tiny number of people with serious genetic abnormalities. And even in their small genetically abnormal groups, the reason for their issues are the same for everyone with the same specific mutation.

99.99% of the population ages and suffers age-related disease for exactly same underlying reasons. The molecular damage is exactly the same. Ditto the pathogens that cause infectious disease. You tailor medicine to the pathogens, to the molecular damage, to the mutated gene in an inherited condition, not to the person. Rejecting personalized medicine is the most cost-effective way to proceed towards mass-manufactured, low-cost, effective medicine.

Fix the inherited diseases with gene therapy. Repair the molecular damage that causes aging. Build the technologies that effectively destroy pathogens. Don't focus on the tiny variations in individual responses to these things before you try to actually address the root of the problem. This is my complaint about personalized medicine in a nutshell: it is displacement activity, distracting from paths that will be far, far more effective in improving health and addressing medical conditions.