Will having sex cause an increased rate of hair loss on men? And if so, is it better to have sex without ejaculating?
It is probably true that there is a relationship between testosterone and sexual appetite. There is also a relationship with testosterone and hair loss and if, for example, a man (who has the genes for androgenic alopecia) applied testosterone creams, he would increase his testosterone blood levels and probably have more hair loss due to the increased DHT. That is where this conversation ends.
Ejaculation (present or not) should not increase testosterone levels. There is no connection between ejaculation and hair loss. If you want to have sex without ejaculating… good luck!