Thread count is meaningless other than as a marketing ploy. The best, most durable sheets were the ones made no later than the 1990s, the earlier 1990s. Thread count was never mentioned, known about or cared about until after then.

Sheet types I stay far, far away from: microfiber, sateen, brushed, Tencil, bamboo, polycotton, cooling, warming, thread counts, any containing petroleum products such as polyester. Any that are made in China.