Jealousy and strife are not just grievous sins, they are foolish acts that can have civilisational ramifications. Many people cannot understand why the West and, America in particular, are acting so foolishly right now as China rises.
Why are we kneecapping our energy sectors, when we have cheap coal, uranium and gas supplies that are practically endless? Why are we hampering our own economies and ability to defend ourselves, by not bringing all manufacturing home? Why are our elites doing so many foolish things that empower the enemies of the West?
Well, because leaders often do not work in the interests of their people, or even their own best interests, but often instead with selfish and petty self-interest. Once you understand this, and you also understand how stupidity is often the fruit of wickedness, because jealousy and needless strife are the fruit of evil, you can see why they act so foolishly.
Evil intentions and motives work themselves out in foolish acts. Even decent men can be overcome with this if they give in to selfishness.
We see an example of this in Hilaire Belloc’s, The Crusades: The World’s Debate:
The critical moment, the turning point in the relations between the Emperor and the Crusaders had come as early as January, 1098, two months after the host had first appeared under the walls of Antioch.
Bohemond had, until that moment, desired that the Emperor of Constantinople should make him, after Antioch was taken, its local lord, under a feudal tie to Byzantium. He had already declared himself in Constantinople the vassal of the Emperor, he had already taken an oath to hand back to the Byzantine authority whatever he conquered. He began by threatening to retire from the Crusade altogether, but he made this threat not to the Byzantine emissary who was with the army, but to the Christian leaders of the host. His threat had the effect he expected, they all but one promised that when Antioch should be taken Bohemond should be made the lord of it. But that one who stood out was the most powerful of them—Raymond. Next Bohemond terrified the Byzantine Emissary, Tactikeos, but he was careful not to make it a personal threat. What he did was to persuade the Greek that the other leaders of the Crusade thought the Byzantines were working with the Turks and betraying them. Tactikeos fled, and with him disappeared the last hope of Byzantine control over the movement. When he had gone Bohemond loudly denounced his treason. After this piece of trickery, typical of that excellent general, great soldier, and bad character, the counterclaim of Toulouse to Antioch was outflanked. Bohemond could make certain of the reversion of the town although (as we shall see) Toulouse held out to the last moment. Bohemond had grievously weakened the Crusade by his selfishness; Raymond of Toulouse by his jealousy. Still, the main fault lay with Alexius. Bohemond could not have played his trick nor Raymond have angered against it if Alexius had sent a sufficiently strong contingent to support the Crusaders, and affirm his regular right. Alexius hesitated to do so from timidity. He had left Christendom in the lurch and it was right that he should pay the penalty.
When later the great Moslem rally had been defeated in the main battle of Antioch, the council of the Crusading leaders just after the victory were still willing to keep their word if the Emperor would take advantage of their offer. They sent Hugh, the French King’s brother, back to Constantinople as their ambassador, to say that if the Emperor would bring or send up an army, even after this long delay to help them in their advance through Syria, and stand with them in the last object of their march, the deliverance of Jerusalem, they would hand over Antioch to him. If he had come with his army, he would have had not only Antioch but probably Jerusalem as well. Byzantium would have appeared again as Queen of the East. The Emperor would not, indeed, have been the absolute master of the Levant as his predecessors had been for centuries; he would only have held its authority through the aid of the Crusaders; still, the Crusade would have fallen within the orbit of the Eastern Emperor, his empire would have been restored; probably Egypt also in the long run would have been recovered. Above all there would have been sufficient Christian strength in Syria to master Islam for good.
The Emperor did not march: no Greek army came. I have said that his failure was a failure of timidity; but it was perhaps also in some part a failure of means. He may have doubted whether he had sufficient forces to detach for such a march—and we must remember that the request was made in the height of summer. Later on, after the Crusaders had wasted the whole autumn and half the winter, in possession of Antioch, indeed, but delaying to go forward, the Emperor, in the April of the following year, 1099, did propose to send a contingent and join the Crusaders in their march on Jerusalem. But it was too late, Bohemond by that time had consolidated his power, and there was no ousting him. All the forces remaining with him in Antioch were lost to the Crusade.
Though this first Crusade succeeded, it was weakened by jealousy and strife in ways that eventually caused the Crusades as a whole to fail. Men concerned with their own fiefdoms selfishly co-opted the Crusade and placed it on weak foundations. This characteristic of leaders is more the norm, rather than the exception.