The phrase "to support the cast" means to provide assistance or aid in some way, particularly by providing financial backing for a project. In this context, it refers to the act of contributing money towards the production costs of a play, movie, or television show. This can involve investing in the project as an individual or through a company, with the expectation that the finished product will be successful and generate profits. By "supporting the cast," one is essentially helping to ensure that the creative team has the necessary resources to bring their vision to life on screen or stage.