The first two Purge movies have done incredible business grossing nearly $200million worldwide and only costing a combined $12million to make. You don't need to be an accountant to realise, that's very good business.
So, it comes as no surprise that Universal studios has announced there will be a third Purge movie and will continue to be written and directed by James DeMonaco.
Regarding this news, DeMonaco said;
"I never imagined that The Purge would become the phenomenon it has become and I am thrilled to continue my collaboration with Blumhouse, Sebastien Lemercier, Platinum Dunes and the great team at Universal in building The Purge into a worldwide franchise."