Your strawman argument is that the solution to problems is just discipline.
That is not true, and is also not what I wrote, which was that discipline helps the mind.
When discipline is mentioned, is that it is used to focus on what is, finding ways to change what is into what it could be, and then doing it without despairing all the while.
There have been people that were able to overcome situations worse than what you used as an example, and there have been people that failed to overcome situations qualitatively and quantitatively less bad.
You are correct that it is arrogant to claim others should behave in a certain way without the experience of doing the same in similar circumstances, but that is neither here nor there.
I will give you a couple of solutions to the problem that you mentioned:
hunger, your children don’t eat too well, you have no work, your wife is ill, you have no resources, you have rent to pay, you haven’t recovered from an injury, the kids are skipping school, they’re mixing with the wrong crowd, you know drugs are involved, one of them is arrested, he goes to prison.
Maybe a course of action would be:
1. suicide - giving up.
2. suicide bomb some entity you blame for the situation.
Or it could be:
2. accept that the situation is bad, but focus on what you can do to make the situation better.
2.1- Perhaps an act of violence against the authorities is in order - if you die, at least that is one less mouth to feed or wail about the terrible helplessness you must endure in life.
2.2- Perhaps you can butcher the wrong crowd as a source of food, which can make you stronger and helps your wife heal, and then you move out to a more affordable place- a cardboard box in the street. Then move on from there.
Perhaps any number of actions are available but you did not mention them in your exposition of a bad situation.
Discipline of the mind may help you find a course of action - any course of action - that has a possibility of improving your lot, instead of doing nothing but moping.