What about socialization do you not understand? This is how men are taught to think in our culture and although not all men take this to that extreme, it's pretty common for powerful men. It's part of how a patriarchal dominance hierarchy system works. Those near the top of the hierarchy use and abuse others who are weaker for their own purposes. It’s literally the definition of what patriarchy is and means — well beyond the gender aspect alone.
In other words, patriarchy is at its heart a dominance-based hierarchy where might makes right, and those who have the most social power have gotten it by intimidation, force, and coercion and by maintaining traditional power once it is established. This is typically accomplished by keeping those further down the pecking order from having an actual chance to compete. Ruthlessness is not only an accepted method of acquiring and maintaining power, but for many, it actually reads as a leadership quality, even today.
Testosterone is not the culprit - a culture that objectifies women and teaches boys (even today via porn, and mainstream media) that women exist for their pleasure and enjoyment is. That's the only "wiring" in play - the influence of our culture.
Edit: Read this story for a better understanding of what testosterone actually does and does not do.
