Venmo users have started to use the payments app to show their appreciation to sports stars or celebrities; in most cases a fan sends a few cents or a few dollars, the practice has helped Venmo increase their user base but can also put them in a precarious position; sports players receiving money for performance can be considered gambling, which is illegal in most states; sending some money to celebrities can open up the platform for fraud as they might not always be sending to a real person but an imposter; this has become a byproduct of how the startup was founded as the social aspect is core to what Venmo does. Source.