What you said is not true, ginsan.
discretionary income is any amount of money that you still have after you pay your expenses.
Discretionary income does not need to be fixed or stable.
Sure, it is helpful to have stable and/or fixed income but it is not necessary.
If you say that a person needs fixed and/or stable income in order to buy bitcoin, you are adding an additional condition that is not necessary even if it might be helpful.
It is like saying that I need to have $100 every week to invest in bitcoin, and if I only have $50 this week or some weeks I have $10 and other weeks I have $200, and some weeks I do not have any, and the punchline is that there is a lot of variance in my discretionary income, yet I still can invest in bitcoin, even if those amounts and/or those frequencies are not known in advance.
It's the beauty of Bitcoin that we can continue with any amount. If in a particular week I don't have any money or less money compared to what I am investing then I can compensate that in future when I have additional money. The key point is never stop investing in Bitcoin specially those of us who are new and don't have enough Bitcoins. The results of continuous investing into Bitcoin will be seen after 5 or more years and then one can feel proud of his decision of investing in Bitcoin. In start it may look boring but after 5 or more years it will be full of excitement.
Yes, I agree with you JJG, the so-called discretionary income is really not fixed, because sometimes our expenses vary every month. Because it is not uncommon for raw materials for food and other things to increase. Because it is undeniable that inflation always lurks around us all and we can feel it. That is why if we base it that when investing in bitcoin we must have a fixed discretionary income, I think that assumption is clearly not quite right. Because basically discretionary income is cold money or the money left over from our shopping for our needs. So it will definitely be difficult to make discretionary income truly stable. Therefore, don't worry too much about this, if we do DCA in bitcoin, then we accumulate according to the discretionary income we have. So it doesn't have to be the same nominal in each accumulation. Unless you already have cold money, for example 1K dollars, and will be invested using the DCA strategy, then if so, you can accumulate the same amount every month. For example, 100 dollars per month, then within a period of 10 months you can be stable in your accumulation.