I have noticed that a small neodymium magnet can get my fidget spinner going at a relatively low velocity compared to what I can get from the force of my finger. I think I know why it is possible to spin the fidget spinner with a magnet and why I can't get as fast a velocity using the magnet as I can using my finger.
First off, the ball bearing inside of the fidget spinner is magnetic so it is definitely a steel ball bearing. Second, the metal on the outside is paramagnetic enough to be noticed in the air when I hold the small neodymium magnet still. I suppose the outside of the fidget spinner is made of either aluminum or austenitic stainless steel but more likely aluminum because titanium, while paramagnetic and sometimes used for fidget spinners is a very expensive metal. I think it is more likely to be aluminum since I notice this paramagnetism with it being in the air. I think you would need a water bath to detect the paramagnetism of austenitic stainless steel. I mean aluminum is more paramagnetic than austenitic stainless steel.
Now, I move the magnet, trying to keep it in the same orientation and trying to keep it from being too attracted to the ball bearing. This produces eddy currents due to the conductivity of the metal and thus the fidget spinner starts rotating. As I keep moving the magnet, the fidget spinner accelerates until at some point, I can't keep up with the fidget spinner's rotational velocity using the magnet and the force from the magnet accelerates the fidget spinner in the negative direction, i.e opposite the direction of rotation, bringing it to a stop.
Whereas with my finger, I can get the fidget spinner going for more than 3 minutes due to the inertia that resists change in velocity.
But am I right on this? Is this why I can get the fidget spinner going with a magnet but not as fast or for as long.