Human should never be subject to any sort of mandatory work. To expect it, even if just a social expectation, is tantamount to expecting people to be slaves. If a person suddenly benefits from a windfall and is no longer in the financial position to have to work then we should be happy for them.
Of course it's okay to quit your job. It's a free country, and you can quit your job even if did not win a million dollars. People are under no obligation to work if they don't want to. The only exception is if somebody signed a contract to work for a fixed interval of time.
People work to earn money to be able to purchase the things necessary to survive, such as food, shelter, and clothing. If you win a million dollars, that job is no longer necessary. There is no obligation to keep the job. The only reason to do so would be because you enjoy it and don't feel like working while doing it.
I do not see anything morally wrong with a person quitting their job if they were to win a million dollars. I do not think a person owes anything to a work place other than giving them their time and effort should he decide that he wants to get a paycheck.
The idea that any individual should be in a position whereby that is considered morally justifiable is to me, foolish. At the end of the day, production is required for resources, and somebody has to provide those resources for consumption. For somebody to benefit from that without contributing their share of work is unfair to those who do.
Of course not. Well you are not obligated to stay at that job unless you signed a contract, you did make a commitment to your boss and co workers to work there. Besides, if you have a job, then you will be able to spend your million and still feel safe from debt. Besides, wouldn't you like to pay off all of your debts and still have some cash left over to support you and generations to come? Keeping a job would allow you to do this.
The reason we have jobs and put up with bosses is for the profit. Without a product, that being vegetables in a garden or a paycheck at the end of the week, there is no reason for the work. A person may still want to work after getting such a large sum of money. However, a boss hardly has leverage over that person anymore. The military discharges lottery winners for this very reason. There is no way to instill discipline.