O why did opening up the santa fe trail to commerce ultimately lead to the destruction of the comanche empire

It was because one of the Comanche's most essential trading objects, bison, was ruined and greatly weakened the tribe economically.

The Comanche refer to a Native American tribe which belonged to Great Plains and its name has an interesting meaning. Reportedly the name "Comanche" originated for a Ute word which meant "Someone who all the time wants to fight me".