When you're an athlete at the top of your game, you have to get your practice in every chance you can get. Kobe Bryant used to wake up at 5 am to practice free throws hours before anyone got to practice. That's the dedication it took to stand out. The same thing goes for soccer, though I don't know how effectively this will actually improve your game. Maybe in the wheelchair leagues.
Isn't this also just a chair with a net on it? I don't know how much these cost, but if you want to make your own version, just put some grocery bags around your chairs. It's the same thing. That's if you can even get the ball in there. You'd have to be an ace player, and I think most ace players opt for the real thing.