Hello there! I think I have a good explanation to answer your inquiry:
Basically, Bauby is bitter over his physical condition and the fact that he's drooling trapped inside a mental hospital. The patient's sense of wit and mind are going strong, but his physical condition is a repulsively frail annoyance.
Before his illness, Bauby was priviliged and successful; he had tidy fabrics, ate fine dinners, and presumably slept with little worries on his conscience. More relatedly, the now-ill big shot wore cashmere and draped blankets made of the same material on his furniture. Cashmere, to him, symbolizes the wealthy life and proud identity that he longs to have again, but can't because of his sickness.