Mostly because of what it does to you & how each person is different. Their bodies may be doing that based on the strain of their environment & then utilizing the changes to better function. Someone not under the same strain or need doesn't really have a reason to have those levels. This manifests in many men as frequent headaches, feeling sluggish, or having more brain fog than normal. As with most things in TRT, symptoms are king.Do you have those symptoms? Time to check your RBC. Is it high? Then the best way to check if that was the cause is to donate. Did the symptoms dissipate after a week or so? Then it was probably the RBC issue & you know high hematocrit isn't what your personal body likes.It also potentially contributes to cardiovascular disease. Since there's no real benefit to having high hematocrit for the average guy & that it typically only causes problems, there's no reason to not donate blood. The main reasons a provider will tell an asymptomatic patient to donate after seeing the levels is because they don't want to be in trouble for missing something if an issue arises.Personally, I need to donate or I get way more headaches while on TRT, that's just how my body is. Follow your symptoms and trust your body.