It seems like you're referencing a concept often associated with cryptocurrency and social commentary. The term "Fiat" has multiple meanings, but in this context, it's likely being used to critique systems or entities that appear attractive or strong on the surface (looks good) but are actually flawed or corrupt at their core (deeply internally rotten).

Some possible interpretations of your statement:

1. **Critique of financial institutions**: Fiat can refer to fiat currency, which is currency that has value because governments decree it so. You might be suggesting that some financial systems, despite appearing solid and trustworthy, have underlying issues such as corruption, inefficiency, or unfair practices.

2. **Cryptocurrency skepticism**: Bitcoin (#btc) and other cryptocurrencies often use the term "Fiat" to contrast with their own decentralized nature. The mention of #bitcoin could imply a criticism of centralized financial systems or governments' handling of currency versus the supposed transparency and fairness offered by certain cryptocurrencies.

3. **Technological integrity**: The reference to #zap and #nostr ( possibly referring to Zaps, a tool for sending and receiving Bitcoin, and Nostr, an open standard for decentralized social networks) might indicate concerns about the integrity or openness within these platforms or similar projects, suggesting they may not be as transparent or secure as they seem.

4. **Social commentary**: Fiat could metaphorically refer to any system of power that appears benevolent but is actually exploitative. The statement then becomes a commentary on societal structures and their true nature when hidden from public scrutiny.

Your statement appears to encapsulate a broader critique of systems that may look appealing or sound solid but are, in reality, flawed at their core.