I expect your first buy to be in lump sum or possibly an aggressive buy in order to have a reasonable amount of bitcoin in your portfolio. Once this is done and the newbie is not satisfied with the level of his portfolio, he should embrace the DCA with all his heart and follow it. There is nothing to be careful about with DCA, as this method was carefully designed to give everyone a soft landing.
I actually disagree with you on that because aggressive investment is always not Adviseable because there is every possibility that you will get into trouble on the process, however when we talk about aggressive investment you are actually referring to investing all you have or majority of your capital on Bitcoin which is obviously not an investment advice, although we understand how potential and important investing on Bitcoin is but if you are not mindful you could end up on a tight corner.
Perhaps as a newbie who is just starting there Bitcoin journey I think the best way is not even to Lump Sum because he doesn't really no much about Bitcoin yet so the main focus should only to accumulate Bitcoin through DCA method because from there he will be free from some certain risk or missing out buying opportunities and also through the use of DCA he will now get acquainted with the ways of Bitcoin and from there he can now decide if he could utilize the Lump sum method and at the time continue with his normal DCA method.
It doesn't matter if a newbie lump sum to take advantage of buying more bitcoin since he feels that he started his bitcoin journey late. As far as the newbie understands what he is doing and have already have faith and believe in bitcoin and plans to invest in a long term investment. If he has already prepared himself ahead of his bitcoin accumulation journey by keeping his emergency funds and reserve funds, and also money funds that will take care of his monthly needs.
It is always said to start as a newbie with DCA strategy, so that those who don't have much to invest would not be waiting to save a big amount of money first before they can think of investing. But if they start with DCA, it will give them the room to continue accumulating bitcoin regularly weekly or monthly based on how much they can afford to use in buying that wouldn't affect their other expenses, so that they can grow their bitcoin portfolio bit by bit when they are consistent and persistent with their DCA strategy, till when they have strong faith and believe in bitcoin after maybe one or two years of investment, he can increase the amount or when he have the money to lump sum, then he can do that.
What about the rich guys that do not care about buying bit by bit for a start because they have the money to lump sum, will you now say that they did the wrong thing. No...a newbie can lump sum or buy aggressively as long as it wouldn't affect his financial life, that will make him go and sell his bitcoin. I started my bitcoin journey with a lump sum that I got from the rent that my tenant paid me, and after I lump sum, I continued with my regular weekly buying using DCA method.
As long as a newbie can lump sum, and continue with his regular DCA purchase, it is not a problem and he will have a better chance of having more bitcoin than someone that started with only DCA. We know how our cash inflow is and everyone has the right to invest based on his cash inflow, and it is not a must that newbies should only use the DCA strategy, when they have to money to lump sum and continue with their DCA. The most important thing is that you keep on buying without stopping as a newbie to increase your bitcoin investment portfolio.