He was probably so not because of malicious intents or motives, or a nasty personality, but psychological stress due to his stacking family tragedies. His wife was assassinated by Anarchist (one of six sitting heads-of-state and two spouses of heads-of-state successfully by that group around the Turn of the Century, also including Czar Alexander II of Russia, King George I of Greece, King Constantine I and Queen Draga of Serbia, King Umberto I of Italy, President Henri Carnot Sadi of France, and President William McKinley of the United States). His only son and original heir, Rudolf, committed suicide along with his newlywed wife in their marriage cottage. His nephew, and second heir, Archduke Franz Ferdinand insisted on marrying well below his station (something not supposed to be done by Royals or high Nobles back then) by marrying Lady Sophie, the scion of a minor Slovak Noble house. The two of them were very assassinated by a Serb Nationalist. It's believed by many, and quite credible, that his behaviour was not intentional malice or cruelty, but his being very harsh familial tragedy psychological strain.