Okay just consider the transaction fees it will take each time you try to withdraw a small unit of Bitcoin from your exchange to a non custody wallets, so it looks unprofessional even if a newbie may not understand this but it is still important for them to know because those amount that would be lost as transaction fees can still be retained if you consider accumulating a larger amount before withdrawing out from an exchange.
Let's say your weekly DCA is $50 and you know that withdrawal fee will be needed you can make it $55 and use the $5 to cover the fee. Before you can accumulate up to $200, you will have $220 worth of bitcoin and when you are withdrawing your asset, the fees won't be much of a concern to you because you have already made provision for it. You can't take because of withdrawal fee and expose your asset to possible risk. If the exchange get hacked you will regret and would have preferred paying the withdrawal fees that would have been more lesser than losing your entire assets. Little fees shouldn't make us fall victim rather let's plan ourselves to accommodate the withdrawal fees from onset.
Well I understand your points but however from your explanation don't you think the investor will lose a lot of money as a fee? Or being affected financially? Because for an investor to choose investing $50 on a weekly basis means that he cannot afford any other amounts higher than what he had budgeted for the Bitcoin accumulation on the weekly basis, so perhaps advising him to add extra $5 could indirectly be regarded as aggressive investment because is very certain is going to affect him on the process which is why in as much as we are always positive we should also consider some challenges that could possibly occurred if taking a certain decisions because having that mindset always guide us very well on our Bitcoin journey.
So actually after considering all this fact I think the best way is to utilized the Consolidate method of investment which simply means that instead of accumulation and withdrawing your accumulated Bitcoin from the Cex you could possibly give it months interval and by then you have gotten a huge amount of Bitcoin that you can possibly withdraw at ones into your custodian wallet and by then the amount you would have use as a fee will be very smaller compare to withdrawing on weekly basis.