Exactly this is the best way to teach them and if anyone will start this method so with passage of time he/s will understand the how important it is and they will be in profit after 3 to 4 years uth they will continue this strategy for long time.
When I have not started using the DCA method, I have tried a few times to teach people about investing in Bitcoin. Unfortunately, the approach then was to put any amount they could afford with target of selling when the profits comes in. Then the hype of Bitcoin was at the peak and the internet was littered with testimonies of people who made huge amount from investing in Bitcoin and some other shitcoins. So my job of convincing them to invest in Bitcoin was not hard and some of them actually joined, saw profits within a short time and some sold while some others held for longer time.
What I later realised was that seeing how easy it was to make profits in Bitcoin, a lot of them went and sourced for more money to invest more without letting me know... some even borrowed money and bought at the peak. For those of them that could not sell when they should and are not ready to hold for long, their pains were expressed in various degrees and I listened to the agony with utmost surprise. Humans can actually be greedy and unpredictable.
Assuming I knew about the DCA method then, that would have made the job perfect because they would have started off with it already thereby eliminating the panic buy attitudes and quest for quick profits.