Spongebob Legos

My son Kyle bought a Spongebob Lego set. It's cute and once it was built, then what? I am trying to figure out why he who has army of lego shoulders, brigades of Bionicles, an arsenol of Nerf guns, a library of computer games, cities of Lego bricks, a space port full of star wars legos possibly need Spongebob Squarepants lego set?