You could use things like being able to outperform the market, being consistently ahead of the Overton window, finding a reception for your less objectively verifiable ideas among (a small group of) other high-performing individuals. This doesn’t guarantee that you’re not still a lizardman among the 99.9%+ lizardmen, just in a high-performing contrarian cluster (hence my rule #1), but at least rules out being a crazy person living in a normal world (unless you’re just hallucinating all of the evidence, but there’s no point worrying about that).
You could use things like being able to outperform the market, being consistently ahead of the Overton window, finding a reception for your less objectively verifiable ideas among (a small group of) other high-performing individuals. This doesn’t guarantee that you’re not still a lizardman among the 99.9%+ lizardmen, just in a high-performing contrarian cluster (hence my rule #1), but at least rules out being a crazy person living in a normal world (unless you’re just hallucinating all of the evidence, but there’s no point worrying about that).