By using the DCA method, you can increase the number of bitcoins at many prices so that it will reduce your average buying price. And your purchase price is no longer at $69k but could be even lower so if he can continue investing in bitcoin at the low price, that would benefit him.
its a simple way of opt-in and out of Btc trade without considering HODLing for a long period of time, well it depends on the movements 
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(including accounting for the 9 factors that I mentioned in this post (https://bitcointalk.org/index.php?topic=5376945.msg58719590#msg58719590)) in order to employ a personally tailored approach.
I really need to go through this there're many alot of things I need to understand and I could really make use of it too.