Only thing I can think would to maybe spend 100 hundred dollars. in the same place. in maybe a few states over and then wait a year. If cops come to invesitgate then it means the money is traceable. If not it's clean coast.
If someone is seduced into taking the money, as you suggest, it is likely they'll be seduced by spending it, in ways that might get attention. They don't even have to be obscene spending practices to get attention
I understand the logic of leaving it alone but I think if you are really in that position, especially if you have money problems I think it would be enough to seduce anyone.
I would think fear of imprisonment or being murdered might be just as strong a motivator. No one just walks away from a sack with their million(s) in it. They are going to want it back, & will do anything. Even if it's surrounded in dead people, there's a strong possibility there are more involved, who aren't just couriers.
Even in a case like Llewelyn Moss from
No Country For Old Men, assuming he didn't make the terrible mistakes of returning to the scene (duh) & not searching the satchel for tracking devices, those people still come to investigate, search. They stay a while & sniff around. Maybe a long time, & anyone they see, who even lives near the area it was lost, is going to be suspect. If the local cops know what his truck looks like & people know he goes out there to hunt, that information can be sussed out
If I lost millions of dollars, I'd be moving into town where ever it went missing, & spend a good amount of money to watch everything that goes on there. You are literally a wanted man, if you take it