The way a child is given birth to and the parents will take care of that child for many years spending and providing for him to make sure that he grows up and become an adult who can take care of himself and also take care of the parents when they are old, is the same way we need to invest in bitcoin and grow it through DCA gradually as a newbie so that a time will come when your bitcoin portfolio size has is big. Your money that you invested into bitcoin will start working for you by generating more profit as the price of bitcoin is increasing with timeline, and your bitcoin investment will start be your pride and it will take care of your expenses and whatever you need money for in your old age.
Your illustration is quite alright but I want to ask you from your illustration what if at the point of the parents taking care of the child in other for them to grow up and take their own responsibility then peradventure the parents losses such a child while they are trying to grow up is it a gain or a lost to the parents? See everything we are doing in life is just risk as no one knows exactly what the future holds or how it might turn out to be so also is our investments as we invest not actually because we are certain that we will make profits but because of our optimism towards positivity so anything is expected to happen to ones investment be it on the short run or the long run.
Majority of parents train their children till adulthood and even see their grand children, only few that are unlucky due to uncertainty that lose their children before they become adults. Majority of traders run at loss but only few make profit.
When the source of funds have been established, then the money should generally be divided into three parts which are for basic needs, for emergency needs and then the part for investment. Each of this should be carefully calculated to be able to get them right from the beginning and when that is done, the journey of Bitcoin investment will become smooth and effortless without the panic and anxiety that many investors exhibit.
I think for a newbie getting these calculations right might be a difficult thing cause speaking from experience the best way for anyone to learn these strategies is to start doing them as soon as possible then on the process of doing so you would better start to the reasons for setting up each of them.
It is easy to calculate it as long as you know your total cash inflow for the month, and from that, you can calculate out your monthly needs, keep your emergency funds just like stated by @Odohu based on your own scenario, so that you can know the exact funds that you will use to invest through DCA weekly, or monthly that wouldn't stress your as a newbie. When you fail to have these figured out and properly planned for since you are going on a long term drive, you are putting yourself at big risk and you will fail in your plans because you don't even know your left from your right. Don't play with keeping your emergency funds and basic needs funds sorted out before investing, it is very important.