The trains use electromagnetism, which needs electric current to create a magnetic field. Regular magnets lose polarity due to vibration and heat. The wheels spinning generates lots of heat and energy and will weaken the magnets. Also, magnets can become depolarized through impact. Dropping a magnet can completely kill its strength. Also, to lift a human would require a huge regular magnet, making your board extremely heavy.
Sincerely,
Big Ball Bearings