If he was still in sight I would have taken it and chased after him to beat him down to nick his phone and touch him inappropriately.
No wait I got that wrong...
If he was still in sight I might have gone after him and handed him the cash. If not left it, I could do with the money but he could need it to feed his kids.
Though part of me would be going "Natural selection, he's dim for leaving that there in this world, does he really deserve to eat this week" then another part going "Well, that is a bit of a **** move on your part"