Your attacker may share the data with a third party, but that's true of verified connections too.
But this is a very silly threat model, "I want exactly one person to be able to attack me at a time".
I don't see what's so hard about this:
Plaintext is worst (active and passive attacks possible)
Unverified TLS is better (active attacks possible)
Verified TLS is best (neither active nor passive attacks possible)
For most of the people in this thread, the units are all something like "number of times my house burns down." I guess I'd rather my house burned down once rather than twice, so to that extent your position is not irrational. But the second time is not meaningfully different; the only further loss is maybe a magazine or newspaper that the postal service delivered the day after the first fire and placed on the ashes that used to be my mailbox. It's certainly sad that I won't get to read the paper after the second fire in as many days, but I'm still mostly concerned that my house burned down.
Your units, on the other hand, are inconsistent and surprisingly ordered. Either you really enjoyed the unburned article you read, apparently enough to forget that the rest of your worldly possessions are gone (this is the "at least nobody eavesdropped on my conversation with the MITM" position), which implies that the units are large, or that avoidance of eavesdropping outweighs undetected MITM. Or else you wear an asbestos suit 24/7 because you already assumed most of the world is on fire and don't care if it engulfs your home (this is the part about how you believe HN could someday serve malicious JS, so that origin authenticity wasn't a big deal in the first place), which suggests that the units were small.
Your values are your own, and only you can decide to change them. But the discussion might have been shorter and smoother if you'd acknowledged that others have been using a single, consistent unit called "catastrophes," and that the only numbers we care about are zero and any.
I personally like to have my life/work set up so that I know what catastrophies _can't_ happen (the probablities can be compared to the effort required to boil oceans or waiting until the heat death of the universe).
I'm sorry, but this is either incorrect or a gross misunderstanding of your own threat model.
Most people treat their online self as an extension of their physical self: that means banking information, private personal details, intimate communications, and everything else that's normally private by virtue of physical ownership needs to go through an authenticated channel.
You might not care that someone can't MITM your Wikipedia traffic, but you almost certainly care that someone can't MITM your tax returns or your medical records.
So presumably, you'd demand a cert from a trustworthy authority in those cases. But you still don't want your ISP to be able to inject ads into the recipe blog you're reading.
But I don't trust news.ycombinator.com any more than I trust somebody pretending to be news.ycombinator.com; validating that cert does nothing useful for me.
Yes, you absolutely do. You don't expect news.ycombinator.com to serve you malicious JavaScript, or to redirect you to porn, or to do anything other than serve churlish content from the Internet commentariat.
I absolutely do not trust this site (or most sites) enough to run arbitrary javascript it serves.
Thus it can be the eavesdropper, easy.
Even if you're being MiTMd by a criminal organization, you aren't also being listened to by the NSA.