Everyone should save for the future. Focus on your main goal. Try to save as much as possible from the current income. If you invest $50 of your current income in Bitcoin, your investment will continue to grow over time. Your invested savings will remain in Bitcoin while the value of Bitcoin will increase and your wealth will increase.
And OP's plan to use the DCA method in his investments is great. He OP earns $300 every month with a $50 plan for a Bitcoin investment of $300, of course this OP plan has already been implemented by other Bitcoin investors with monthly income greater than OP's monthly income. This investment strategy is good enough to be used by everyone with different incomes because they make regular purchases. If one day his income rises from $300, OP can increase the amount that will be allocated to Bitcoin investments.
It's a smart savings method.