Cash on the floor isn’t luck. It’s somebody’s bad day you get to fix or make worse.

Money on the ground got there because somebody lost it, and whoever that was is probably retracing their steps at this moment. Framing it as a windfall requires not picturing them, which is easy enough and takes a small amount of deliberate blindness. The choice in front of you is about a person rather than a sum.

Hand it to whoever runs the place and say where you found it. If there is nowhere to hand it, wait a minute and look around you. The twenty matters far less to you than the hour it would cost them to lose it.