It's quite unlikely someone would risk burning a viable 0day without either going wide (and then we would've heard from a few more people) or going after a well outlined target that would be guaranteed to be worth more than the 0day itself.
The person in question is very wealthy. I know at one point his portfolio was 9 figures. That may have been at the peak of the bull market but I imagine path is still very rich. Is it worth a 0day, still not sure.
I guess my prior based on the way this guy was talking was that he probably had at least 6-7 figures in crypto stolen, which is worth it for a mid tier 0day. Especially if you think it's unlikely to actually get burnt.