You might not be able to explain why magnetism works, but you can at least be sure that it doesn't violate any fundamendal physical laws - such as conservation of mass-energy, or the laws of thermodynamics. You have to put in energy to overcome gravity, whether you can explain the effect or not. In broad terms, this needs to be given a pinch of salt of comparable size to that given to make a perpetual motion machine work.
Yes, I know that mass-energy and thermodynamics probably aren't "absolute", but they don't have big enough holes in to hide a competitive anti-gravity device.