Idk my kid has bombas and Walmart socks and there is a significant difference in quality. Maybe only 2-3x better but still difference is there
As to why they are better the toe knit eliminated the seam and hard spot where cheap socks terminate. The fabric wicks moisture better and get material is less abrasive. The knit and fabric all add significant additional cost to the fabrication process. Look up some videos on you tube on how socks are made.
Some brands are objectively much better, since they support my feet better, have no seams around the toe area that drives me nuts, wears better (my cheaper socks get holes in them in about a year), it breathes better, it reacts to moisture better, it stays up on my ankle better and doesn't slide down, it doesn't twist on my feet because it holds the shape better, and it's cushioned better among other things.