The die size of the B580 is 272 mm2, which is a lot of silicon for $249. The performance of the GPU is good for its price but bad for its die size. Manufacturing cost is closely tied to die size.
272 mm2 puts the B580 in the same league as the Radeon 7700XT, a $449 card, and the GeForce 4070 Super, which is $599. The idea that Intel is selling these cards at a loss sounds reasonable to me.
Though you assume the prices of the competition are reasonable. There are plenty of reasons for them not to be. Availability issues, lack of competition, other more lucrative avenues etc.
Intel has neither, or at least not as much of them.
At a loss seems a bit overly dramatic. I'd guess Nvidia sells SKUs for three times their marginal cost. Intel is probably operating at cost without any hopes of recouping R&D with the current SKUs, but that's reasonable for an aspiring competitor.
The only way this would be at a loss is if they refuse to raise production to meet demand. That said, I believe their margins on these are unusually low for the industry. They might even fall into razor thin territory.
272 mm2 puts the B580 in the same league as the Radeon 7700XT, a $449 card, and the GeForce 4070 Super, which is $599. The idea that Intel is selling these cards at a loss sounds reasonable to me.