i actually agree with her.
if time was infinite, sure. but, i'd guess that pelosi is more aware than most that it is in fact not.
they're better off writing legislation, and trying to avoid the perception of being a do-nothing congress, which is what took them out the last time.
it's less that he's not worth it, and more that there's more pressing concerns to deal with.
https://www.nbcnews.com/politics/politics-news/nancy-pelosi-impeaching-trump-he-s-just-not-worth-it-n981941