For five years, possibly no event has brought more people to Riviera Beach than Sincere 2000's Boxing for a Cause.The organization was founded after a personal tragedy. In 2018, Unique Melvin and his wife lost their son, Sincere Melvin, to suicide.WATCH WPTV'S COVERAGE BELOW: Sincere 2000's Boxing for a Cause draws Riviera Beach crowds for mental health and domestic violence"In 2018, we lost our son to suicide, so my wife and I decided that we d…