Answer: Economic, military and personal.
Step-by-step explanation:
When we talk about economic reasons, Constantinople was a very important hub between Europe and Asia. Constantinople is the most important connection on that road. Therefore, the conquest of Constantinople was of great economic importance.
At the time of the conquest, the Ottoman Empire was in the process of expanding its borders. Constantinople represented the starting point of the Ottoman conquests towards Europe.
Mehmed II, who conquered Constantinople, dreamed from childhood that he wanted to conquer Constantinople. That was his greatest wish. Therefore, the conquest of Constantinople was both a personal project and a wish of the sultan.