USDC is backed by cash and cash equivalents (treasury bonds, for instance). They've gone through multiple audits, and are in the process of going public.
The cash equivalents is highly rated securities and it's unclear what they define as highly rated. They don't disclose the securities they are hedging with, plus they mention that they are actively trading with this money (so there is some additional risk even if they are trading solely treasury bonds).
2. You want "a stable value" but don't really want to hold USD (because to hold USD, you need access to the US capital markets and banking system).