Edward Snowden exiled in Moscow, Julian Assange jailed in London, and Chelsea Manning jailed in Virginia remind all of us every day what happens to people who reveal classified information.
If Democrats cannot convince people to remove Trump from office, the proceedings will have been a colossal waste of energy, at a time when the party cannot afford to make errors, or waste any of its paltry assets.
Trump and his allies in the Senate need only time the vote for his acquittal during the week before election day. That makes for good political theater: vindication for your supporters, and total deflation for your opponents.
Nancy Pelosi wants to keep her job, of course, but she also focuses on what the party must do to defeat President Trump. You do not seem to think a unified party leads to that outcome.
If resentment toward Sanders persists so long after he stirred up considerable enthusiasm for Democrats in 2016, you want to ask why. It tells you this party does not want to win.