Maybe it will take them 10 years or more to reach a point - at least getting used to BTC investing. DCA is really difficult to manage due to the lack of consistency of expenses and excess cash supply compared to an individual's income, in addition to having a separate source of income in this case. But you may not have other options to increase your income or spend most of your day in your current job. I think in terms of investing, even if it's on a small scale or in small amounts, having the habit of accumulating your BTC by following the DCA method will allow your portfolio to grow over the years
One of the beauty of investing in bitcoin is that one may decide to start with amount as low as $10, to start his Bitcoin accumulation journey, and as time goes on he or she may decide to increase the amount of their bitcoin accumulation depending on their cashflow at that time. One thing we should know is that we can start our Bitcoin accumulation with any amount, but still our profit we may endup making still depend on the number of Bitcoin stashes in our portfolio. That's why we have to be consistent with our accumulation and same time be aggressive, without over doing it.
Bitcoin is not like other coins , that may not bounce back whenever they experience a massive decrease in price. Though it may take time but Bitcoin always bounce back stronger, Like around 2022 Bitcoin experience a massive dip to the price range of $15k and it's started falling from the price range of $60k if am not mistaken (because is Kinda fuzzy now). Well then alot of folks sold their coins, and same time alot of folks also thought that Bitcoin may not recover back. But now look at Bitcoin has even created a new ATH and we all believe it ain't stopping there .
So there's no reason for one to be scared of investing in bitcoin (though there's no guarantees, but still worth it), or procastinating now . Because you may only endup not doing yah self any good .