Politics is inherently about convincing people to move to your position. Another reference point is the difference between "strategy" and "tactics."
Democrats are both extremely confident in the power of strategy and extremely inept in the concept of tactics. Strategy tells them that they should not take the first step until they have a path charted for the journey. Tactics tells them that they can take the best available first step and use new information gained from that step to plot the second step, and so on.
Your casual disregard for impeachment, likening it to "lifting skyscrapers off their foundation," reveals that you cannot imagine a tactical approach, which epitomizes the problem with traditional democratic thinking. You think because two impeachments failed, it's moronic to try a third without some incredible game-changing development.
Instead of that, I'd invite you to think about impeachment as a first step that we should take because it's morally required, and because not doing so makes impeachment dead letter under the Constitution. An impeachment hearing reminds the public what standards are, what standards they should be following, and is an opportunity to sway the public to themselves pressure their senators to convict.
Putin understands tactics, and it's why he now has control of Crimea (and arguably the United States). He has no master plan. But making the best available move to inch toward a target means often you get there, even if unexpectedly.
I'd recommend: Don't be resigned and defeatist, and certainly don't spread defeatism to others who may do what you have decided you can't.