When an investor follows the DCA strategy, an investor may not have discretionary income. Because an investor keeps the amount of his income for DCA if he does DCA and the rest of the money he can definitely use for his necessary work. The money that is left after the necessary work is the money we do DCA. For example, I cannot invest 100% of my income in the DCA method, but I can definitely do 30% DCA to meet my needs. That's why I say that if DCA is done, there may not be any saved money, but it is better to invest in the DCA method instead of waiting for the market to fall.
You can only invest 30% of your income if that's part of your discretionary income because your discretionary income needs to be shared into three equal parts in the beginning of your bitcoin investment. First part of your discretionary income should be for your weekly DCA, second part is for building your emergency funds and the last part is your discretionary consumption.
If you just invest 30% of your income without confirming that's your discretionary income after taking away funds for your basic needs and monthly expenses, you might end up using beyond your discretionary income to invest in Bitcoin which is wrong because when your needs arises, you will sell those bitcoin at a cheaper price to take care of your needs if the price of bitcoin is below your entry point.
Some people have an extra income of $200 per month, some have $2,000. Therefore, the amount of investment in Bitcoin should also be determined according to the person's income, risk taking ability and financial goals.
The amount of money you are using to invest in Bitcoin should be based on the size of your discretionary income and not your income irrespective of the size of your income because some people have income but they cannot get a discretionary income from their income.
Mr A income is $1000 and his monthly expenses with his basic needs is $100 doesn't mean that he can invest with a higher amount above $100. Mr B might be receiving $500 as his monthly income but he's basic needs and monthly expenses is $300 because he's still single, he can put more money into his DCA than Mr A because his discretionary income is $200 which is 2x that of Mr A.