Event like this can possibly cause stampede where some old and young people can possibly get hurt and even death. If you drop this in my place.
I suspect you have had very little interaction with true homeless people if you believe they will stampede over dollars. That is what rich people do. Homeless people are generally very appreciative and supportive of one another in these types of environments. I suggest you take some time yourself to visit with some homeless people in your area. You might be surprised by their generosity.
Please watch this to gain some perspective.
https://www.youtube.com/watch?v=CPdqtktkZn0Honestly this is an awesome idea and I hope everything works out, for all of us. I've donated a couple of dollars... but I don't think that's enough, I'll definitely donate more once the first "drop" happens and all goes well.
Cheers,
monbux