The study found the average effect was no different from placebo. It’s plausible, based on anecdotes like the one you’re responding to, that Prozac is harmful for some people, helpful for others, with the expected benefit close to zero. If so, it might be necessary to just try it and see if it’s obviously helping, keep taking if so, stop if not.
This is, in fact, pretty much the exact procedure: try one type of treatment or medication, see if it's obviously helping, and if it isn't try a different treatment or medication. It's imprecise but it's the best we have.
The problem is that taking certain psychotropic medications changes your brain chemistry. It’s not as simple as it sounds. It’s not like trying on shoes. The brain is dynamic and drugs alter it, as does life experience, talk therapy, disease, aging, etc…
