But I'd assume a huge amount of that net worth is due to Better.com's valuation. Valuation is, of course, just the amount the most recent investors paid for their shares, times the total number of shares. And those most recent investors include Softbank, who also gave the founder the loan.

Seems like a pretty scary loop.

If Better can't itself afford to pay the loan back, bringing the personal guarantee into play, what value will the equity have?

Net worth is an abstraction that's generally useful to reason about outcomes, but it's a leaky abstraction.

Unless that loan underpins the value