Both readings fit the next request--revenge on his persecutors. He says, "I want them to suffer as I did." And, although I'm not admitting anything here, I am willing to say that I can imagine someone wishing that God would do this. After all, the audience in the movie house does clap pretty loud when the villain is taken down.
Jeremiah voices a rationale--It's on your behalf that I've been suffering. I studied your words. I devoted myself to doing what you said to do. I avoided distractions and detractors." Side comment: Perhaps Jeremiah was being truthfully sincere, but the Bible gives us evidence that Israel could not have made these claims honestly. Furthermore, few of us could, either.
Jeremiah then asks, "Why haven't you taken better care of me" What kind of God would let such things happen to such a loyal follower as I have been?"
A couple of points: First, since so few of us really deserve much reward based on how we actually behave, what we want is for God to grade on the curve, give us credit for showing up, or something. We want to live comfortably and for God to act graciously. Second, here's an example of someone voicing a complaint to God. Scripture has a lot of these--read through the Psalms, in particular. Many of them are laments (a nice way of saying gripes).
Now look back at verse 17. He laments, "Because of you I sit alone." He has done what God wanted him to do and he was not rewarded; rather, he finds himself bereft, isolated. John Hayes, in Preaching through the Christian Year A, says:
He never dreamed that being God's prophet would carry such a price. Were his persecutors Babylonians or Egyptians or Canaanites, the suffering could be predicted and even borne with a measure of satisfaction, but it is God's own people who inflict the pain.God's response is in verses 19-21.