What are the reasons for the collapse of the Byzantine Empire?

We are talking about the period from 1200 to 1453, the reasons are as follows:
Internal strife and conflicts, they were at the beginning of the XIII century and in the middle of the XIV. The first led to the destruction of Constantinople by the crusaders, and the second to the weakening of the empire.
Economic crisis due to frequent wars, seizure of trade routes by merchants from Venice and Genoa. This made it impossible to maintain a large enough army.
Attack of the Seljuk Turks from the east in the middle of the XI century and the Ottoman Turks in the XIV-XV century.