Common usage and how we associate words with actions.
Having said that, if you really want pursuit, please use it. But because of expressions like "hot pursuit," I tend to think of other things -- and I want my reader to stay on track, not start remembering The French Connection. But that's just me.
I can, however, see using it like this: In his pursuit of the company's top position, he double-crossed or fired many of his friends. Or, In his pursuit of an education, he did anything he could -- often holding down two or three menial jobs at a time.
I guess I want a little more drama with my pursuit. Not library science.