May update
I learned that I don't want to build another business in an area where I don't have any domain expertise, be it for the sake of making money or because there may be some longterm thesis behind it. I want to work on something that pulls me intrinsically without any rational justification required.
I also learned that I likely do want to found a business, or rather a lab. I can't sustain IC work for long because it feels like low leverage. I like operating within uncertainty, in environments with endless possibilities of thinking outside the box, and where you have to commit fully to high-leverage, often risky, actions. I like being a founder.
The area that pulls me intrinsically, in a way that justification indeed lags behind, is game theory and its intersection with AI. Game theory is what I've been doing my entire life; game theory is what I want to continue doing. AI enables the most interesting, scalable applications of it. I could come up with reasons why this matters or makes economic sense, but no matter how many reasons I can come up with, they would still never justify my actions more clearly than the raw magnitude of the underlying intrinsic drive.
So I'm left with feeling the pull—one that I cannot fully rationally explain the extent of, and never will—and that's exactly what makes following it scary but also superrational.