Cats need mental stimulation. Since you can’t always be around to play with your cat, you need to give your cat a place to play by itself such as a scratching post that it can attack, climb, and sleep on.
Scratching posts often include dangling toys, hammocks, and tunnels for cats to explore. By giving your cat a place of its own, you can keep your cat happy while you’re out working in a job you don’t like so you can afford to buy more cats.