Its an objective fact among every country that publishes crime statistics. These countries all vary widely in every other metric you can imagine (social, economic, political etcetera). But, crime being disproportionately commited by men is a universal constant. Nobody has an objectively correct answer to this question, it's just a prompt for discussion. Share your opinion, whatever it may be. However, please don't be a dick to other commenters. Disagreement, good faith, many view points and discussion is the goal here.
This is it. It's entirely a social cause. There's an unstated rule that males are generally disposable unless they have status and/or resources.
This leads to men with low self esteem and nothing to lose, no hope, taking risks and taking out their frustration on society. It's both for survival, to have some kind of relevance, and because what the hell else are they going to do when the coping mechanisms run out.
I have no idea how to solve this.. but it's entirely caused by capitalism, as per usual. When people are valued only by a dollar amount, this is what happens.