This is an interesting hypothesis, but I think we should consider that the nobles actually believed in the religious aspects of the Crusades. While I am sure some were in it for the money or prestige at least the first couple of crusades appeared to have been motivated by religious zeal.
Don't mistake excuses for motivations. The law of primogeniture (inheritance to eldest son) along with large family size played a big role in the causes of the crusades.
Let's suppose you've managed, as a family, to hack and slash your way to the top of the nobility. Grandfather was a friend of the guy who became king, father inherited lands and got them productive, and now five brothers have all survived. The eldest gets the land. The next four have learned to ride horses, swing swords, and wear armor. One of them decides that the Church isn't so bad, and thus effectively goes into politics. There are still 3 armed badasses who won't be getting the power and wealth they are used to... unless they go and take it from someone else.
Their brothers in the Church have an idea: maybe you can go be violent somewhere else?
This also had a pretty big impact on South and to a lesser extent North America. All the guys who had finally driven the Moors out of Spain only knew how to fight so went off to Mexico with Hernán Cortés to carry on doing more of the same.
