It is not true that every source of income will have discretionary income. Even if someone has a source of income, there may be nothing left after necessary expenses, loans, family, medical and emergency expenses. Remember that having income and having discretionary income are not the same thing. Even if someone's weekly income is $100, if his entire income goes to rent, food, transportation, loans, family or emergency expenses, then he does not have discretionary income to buy Bitcoin. Again, even if someone's income is irregular, if after necessary expenses and a small reserve, $10 or $20 is left, then that is his discretionary income or he can start saving with that.
it means you don't know what you're saying, what is then the financial management we are talking about, mate in every source of income one should be able to figure out his discreationary income, I don't want to go into details of all you listed here, what you are indirectly saying is that someone must have a certain level of income flow for him to have a discreationary income which is very wrong and deceitful, just learn this today, as long as there's a source of income, discreationary income can be figured from it, for your information, what you just did is to create excuses for those with little income to find a reason why they shouldn't start investing in the first place.