Spend some time watching the faces of the people competing against each other - adrenalised excitement, fervour, concentration and intense competitiveness is etched in every expression. Even the people pretending that it's all a big joke, pretending they don't care whether they lose or win, grimace and curse when a mistake is made that endangers their current position.
If people have an in-built will to win, a desire to destroy, a hankering to humiliate their fellow man (or woman) at whatever game/sport happens to be taking place at the time, link games give expression to those urges. Ask the manager of the Trocadero in London which games bring in the most money. He'll point to the rows of machines that let people compete against each other, and then he'll rub his hands together.