"BTC-only" is correct 99% of the time. But being right for the wrong reasons 99% of the time means that 1% of the time you throw the baby out with the bathwater - a catastrophic result.
If the heuristic keeps you safe as an individual but collectively guarantees the worst possible outcome, your heuristic isn't safe. It's an extinction cult.
When your brain is flooded with ambiguous, high-stakes data, the mind rapidly reinterprets the strange lights, shape, or motion as something familiar and less worldview-shattering such as a weather phenomenon (safe natural explanation), because accepting the truly alien would demand far more cognitive and emotional effort than pattern-matching it to known categories.