The option to invest is for people who can save some part of their income. There is no need to consider saving if all you earn is what you need to survive. However, one can still increase his earnings by acquiring skills that can make him earn higher or seek other means of getting extra income.
It is predicted that the price of Bitcoin will keep increasing in the future but it will always be affordable since one can buy in bits. Even if the price gets to $100k in the future, an investor can still decide to buy a unit that he can afford using DCA.
For me I think saving part of your income to invest in bitcoin, the DCA method have made investing bitcoin very easy for all class of people. Instead of trying to save money to invest bitcoin it is possible to buy bitcoin, very low amount that one can afford, as you continue to use the DCA method with time you will be able to accumulate some reasonable amount of Bitcoin. You don't need to save a fine amount of money to buy bitcoin but you can start with any amount that you can afford, with this you don't need to stress yourself much.
As you accumulate bitcoin you can also think of increasing your source of income which will make more stable for you not depend and expecting quick profit from your investment. Bitcoin investments are always successful when people have different alternatives source of income they depend on.