system
Given the following post, respond as if you're commenting on Reddit:
human
[Franz Kafka’s The Metamorphosis] Gregor was able to comfortably support himself and his three family members. After his transformation, why does his family struggle to support him?

Apparently, nobody else in the house worked and yet Gregor was able to support all of them, even planning to send his sister to music school eventually. I understand that Gregor’s father had some debt to pay and this is why Gregor had to keep working at his job even though he disliked it.
Yet when Gregor is unable to work, his family has to endure hell to support him? They all have to get jobs and even rent out their home, with the stress pushing them so far that they stop seeing Gregor as family. They abuse him and eventually leave him to die.

Why is Gregor such a burden? Horror and psychology aside, once they get used to having him in the house, he should be much less of a burden than an actual human. He only eats garbage, does not bathe or need cleaning, he doesn’t need clothing, and he never goes outside. 
Why is his family so enraged they need to work instead of leeching off him? What if he just broke his leg and was unable to work for a few months?
gpt
Gregor was a travelling salesman, selling fabrics. From his own words we know that he travelled far and wide, taking the train to meet clients. We can therefore assume that his job covered at least a county, if not nationwide. He was clearly an accomplished man. He also notes that he does not sell singular items, but sells contracts for said items. Commercial customers often spend large amounts of money at once. If he works on commission, he could be earning a large amount of money. Given that he was a former lieutenant in the army, he probably also had an army pension (which could no longer be claimed as he could not provide any ID).

Given that his (and his parent's) debt is tied to Gregor's boss, it is quite possible that he owns the house they live in and has decided to take the cost of rent directly from Gregor's paycheck (as a tax dodge). Without Gregor working, he cannot do that, which means a quick hike in rent to cover the tax that he would have otherwise had to front himself. Alternatively, he may have allowed them to remain rent-free but added it to the debt, which was called in upon Gregor being unable to work. Furthermore, it is revealed that his employer had recently given a large sum of money which had not been repaid by the time of the incident. It is not told to us whether that money could be reclaimed, which may have added to the debt.

Such a financial burden leads to resentment, and ultimately the fate that we are shown.