Why did Gregor become a beattle?

The Metamorphosis is a novella by famous 20th century writer Franz Kafka, who often utilized absurdism and surrealism in his work. The story follows a man named Gregor Samsa after he wakes up one morning having somehow transformed into an enormous, disgusting bug.
It is never explained outright why Gregor turns into an insect, which leaves room for the reader to come up with their own explanation, or just accept that it is what it is, like Gregor does. However, we can infer something by looking at Gregor's life before his metamorphosis. In order to support his family and take care of their debt, and hopefully one day send his sister to a music conservatory, Gregor has been working tirelessly at a thankless, soul-sucking job. With all that in mind, one way in which we could interpret Gregor's surreal metamorphosis is as a manifestation of how his life has made him feel: lowly, inferior, and inhuman, like a bug.
Becoming a giant insect also makes it impossible for Gregor to work, so the metamorphosis could be interpreted as a transformation created by Gregor's subconscious, in order to get him out of his hellish job.