Why did the crusaders fail to hold onto the holy land?

At that time, the Muslim states were significantly stronger. In addition, feudal wars took place in Europe itself. There was neither the means nor the ability to equip a large army to the east. Thus, the crusaders gradually lost the occupied territories and surrendered their positions. Ultimately, the crusaders lost all of their conquests. At the same time, Muslims were able to move even further. They captured Turkey and even Constantinople itself.