diamagnetic material exist, and no theyre not nearly as useful as a superconductor with 0 resistance.

Diamagnetic levitation is extremely weak, which makes it much less practically useful, and also reduces its entertainment value (if you can levitate things 2 cm above the surface the 2 billion children in the world will be all over the stuff; the 1-2 mm you can get with bismuth diamagnetism isn't particularly impressive.

I don't know all these subtleties, but maglev trains are awesome.

Maglev trains do not use diamagnetism or this kind of permanent magnets. They use electromagnets and sometimes much stronger rare-earth magnets, which are much more convenient and effective. Some of them do use superconductors, though, AFAIK.

Not really, what really matters is what weight it can actually support. Most of these materials can barely levitate a few grams - way below any kind of useful application except for maybe gimmicky toys.

> If something can levitate without being a superconductor it is already useful for a LOT of things.

It is not that useful. Electromagnets are used when we need something like that at scale, such as in maglev trains. Permanent magnets have their uses, but we have plenty of others that are as strong as this, and plenty of others that are much stronger than this. I suppose we will investigate it’s properties and we might find something interesting, but almost certainly not because of its magnetic properties.

Magnetic monopoles would be nice