Why did Caleb Kraft build a massive version of the predatory plant from the Super Mario Bros. franchise? Because he could. A better question: why aren't we all building our own?
Kraft's plant has both indoor and outdoor variants. The outdoor version uses compressed air to shoot powdered creamer 6-10 feet into the air, then ignites the creamer. Obviously he wouldn't want to do that indoors. That's why he also has an indoor version that uses butane to shoot flames about 2-3 feet into the air.
You can watch a video of it in action at the link.