The relevant question is what market sentiment is on the IPO valuation, and how much that's shifted over the past month.

History shows that financial bubbles can and do occur. The market is not inherently rational. Who puts what value on the issue and why is a question that's hard to answer. History has also shown that those assisting in IPOs (e.g., investment banks) may commit to making purchases at specific price points in an attempt to bid up prices. Which is to say that the market is neither transparent nor entirely free or fair.

Again: the broader point is that VC manage a portfolio of investments, Reddit is one asset in that portfolio, and that calculus may well consider a 2x return as little different from a 1x or even a loss, relative to the possibility of a 10x+ exit.

Or to use the sportsball metaphor: this appears to be a Hail Mary pass.

And quarterback is about to get sacked.