It's not irrelevant -- it's the same story every time, just with a different company.

The "underlying issues" are things Uber management (1) understands better than outsiders looking in; (2) they're actively working to address; and (3) they have vastly-superior metrics to understand their own internal growth rate. They want to stay private precisely for this reason: They don't want to answer whiny questions from people who think they know better.

"Wildly overpriced" is speculative on your part (at best). This isn't a publicly traded stock. It's preferred stock, and valuation is ~1 line item in a contract that probably spans dozens of pages. Those other T&C's matter a lot: liquidation preference, participating preferred, etc. Those newest investors are certainly getting superior liquidation preference, and likely getting guaranteed ROI.