Some men may prefer blondes to brunettes for a variety of reasons. For example, blondes may be seen as more attractive or feminine, or they may be seen as more outgoing or fun. Additionally, some men may have a personal preference for blondes, either due to a past experience or simply because they find them more aesthetically pleasing.
It's like saying that some people prefer one type of food over another; it's a matter of personal preference.