Okay an example. You invest 10 pounds each and get 100 people to do this. You have 1000. The sort of return you'd expect to get based on sensible investing could be maybe 5 or even somehow 10% in a year.
So for all that money you make 50-100 pounds for tf2 in a year.
You might as well just all donate your original money. Unless you agreed to invest in risky as fuck stuff. You could maybe do that as nobody would care of they lost 10 pounds