What reasons prompted the Europeans to go to the crusades?

Speaking about the Middle Ages, one cannot but mention the Crusades. The Crusades to the East were conceived by the Pope. The reason was that Muslim Arabs began to appear in Byzantium and Jerusalem. Many of them destroyed temples and monasteries. And the Crusades became the cause of the salvation of Christianity in the East. But, in addition, the Pope and the Europeans who responded to the call sought to replenish their own treasury through these campaigns, to extend their influence over these lands. The Crusades continued for over two centuries.