What political motivations did they have? Was it just religious piety and devotion to the Pope and the Church? Was that enough to abandon the prospect of consolidating power at home?
This question has come up several times in the past so here are some previous answers:
First, there's this classic answer from the FAQ:
What kind of specific examples/evidence exists to support the idea that the Crusades were motivated more by the prospect of collateral wealth rather than religious goals in the Holy Land? by /u/Medievalismist
And then two recent answers by me:
and
As I always like to say, there may be as many motivations as there were crusaders!