He was considering a run for the presidency after Andrew Jackson left office. However, when he lost his seat in Congress his political ambitions came to an end.

Texas represented a land of opportunity at the time. After Mexico won its independence from Spain, it decided to populate the area of Texas with Anglos from the U.S. After several years the plan failed, and the Texicans began to seek independence for the new Republic of Texas.

The founding fathers had huge egos as well as ambition. Austin, Houston and Crockett all foresaw themselves as future presidents of the Republic of Texas. Travis also aspired to a political future. This was particularly attractive to Crockett who was was still smarting from his loss in Congress.
Bowie on the other hand left Louisiana one jump ahead of the sheriff. It seems there was some "difficulty" with the validity of deeds to Spanish land grants that he was selling. He married into the Mexican aristocracy, and acquired huge land holdings in Texas. Consequently, he had a lot of self interest to preserve.

All in all sounds like the good old American way.