Hmmm. Wikipedia agrees with you that it's a solid. But the explanation of why it's not a fluid is handwavey; their strongest claim seems to be that experiments

Hmmm. Wikipedia agrees with you that it's a solid. But the explanation of why it's not a fluid is handwavey; their strongest claim seems to be that experiments show that it doesn't flow on any reasonable timescale. But presumably that's at standard temperature and pressure; the article doesn't mention the conditions. https://en.wikipedia.org/wiki/Glass#Formation_from_a_supercooled_liquid https://en.wikipedia.org/wiki/Glass#Formation_from_a_superco... Like, glass is definitely liquid if you get it hot enough. But it doesn't have a melting point; there's no discernible transition from hot glass to cold glass.