Why did the Greeks defeat the Persians, and after 150 years lost their independence and freedom?

This is due to the fact that when the Persians invaded Greece, part of the policies united to repel the enemy, thus, the Greeks were able to repel the attack of the Persian troops. When Macedonia began a war against Greece, there was no such unity between the Greek cities, and therefore, after the battle near Chaeronea in 338, most of the country fell under the rule of the Macedonians.