He was just as this prophecy stated, he was stronger and richer. He commanded the largest army in history and led a major attack on Greece, a completely devastating defeat.
The kingdom of Persia had its own demonic influence like every nation does, even the USA today. There are demonic principalities doing everything they can to keep this Nation from honoring God in the way it was created. The demon's main job is to work against the people and the plans of God.
Not only weeping because of a grieved spirit, but he was also fasting. This fast was a type of fast where he did not eat any preferred foods. You know the comfort foods we love, pizza, mac n cheese, mashed potatoes, cheeseburgers, etc.
Daniel was hearing from Gabriel the future of their coming Messiah. The very one they were looking forward to, and it was grim. To hear that your Messiah, the one who was to come and save the world will die a horrible death had to be shocking for Daniel.