This Bytedance investor and conservative megadonor is really not having a good month.

Every so often, a guy comes along who is all of a sudden everywhere—a zeitguy, if you will. In 2024 in American politics, that guy has been Jeff Yass. Yass is in his late 60s and has been a major finance-industry player and Republican donor for some time. (He is one of the co-founders of the Philadelphia-based Susquehanna International Group, a trading and investment company, and is worth an estimated $40 billion—making him, in a phrase that for some reason is repeated quite often, the richest man in Pennsylvania.) But this year a number of developments have put him much…