Ehhh... not quite. There's evidence that copper runs closer to the speed of light (aka c), than fiber. Light through glass runs at around 2/3 c, making it the slowest option.

Wireless technically runs as fast as light, through atmosphere that's a tiny bit slower than c, but as close as we can get.

There's also a large argument among physisicts and electrician YouTubers about the speed of electricity through a wire, and I don't understand the conclusions, though they were articulated quite well by the YouTubers, it just didn't stick in my brain. The premise is how fast a lightbulb would illuminate if it had one light-second of pure copper (or superconducting) wire between the power source and the bulb, with little to no resistance. It's interesting but nuanced and complex.

Wifi, being EM waves (same as light) should run the fastest, copper ethernet close behind and fiber dragging it's heels at 2/3rds c. However, in practical applications, wifi has more to overcome since it's a shared medium. Copper and fiber have a dedicated medium, so they have no competition in signaling, wifi needs to contend with everything from other wifi networks spurious emissions from other frequencies, even background cosmic radiation, as well as itself (half duplex). Because of all of that, you generally end up with wifi in last because it has so many protections and checks that it delays itself to ensure that it's transmission will be recieved intact. The packets are generally larger and take longer to get started, so all the additional (mostly artificial) slowdowns make it slower. However, if you use highly directional antennas, a pair of them, on different but otherwise equivalent frequencies for send/receive, and cut out a lot of the other factors by designing the system well, then disable most of the protections because they're not needed by design, it will be faster, at least in terms of latency, than fiber or copper in almost every case.

Since designing a multi-access system that doesn't need wifi's protections is borderline impossible, this is limited to very controlled point to point systems where both ends are tightly constrained.

So the argument "wifi has a lower minimum latency" is correct, but irrelevant in 99.99% of use-cases. Copper is easier and cheaper than fiber and actually runs faster, than fiber, but it's only viable for extremely short runs, up to 100m in most cases, and fiber, while "slow" at 2/3rds c, is better for longer distance since there's less line-loss across the glass per foot.

This is a very deep topic and I'm no physicist, but I've been endlessly fascinated by this issue for a very long time. The information here is the result of my research over many years. I still consider fiber to be the gold standard of data communication, ethernet to be next-best and overall best for relatively short connections, and wireless to be dead last due to all the challenges it faces that are not easily overcome.