Bitcoin isn't that volatile for the time being; the past few months, up to a year or even more, have been relatively stable, ranging between $25.000 and $28.000. With that being said, the DCA technique is quite effective in such cases since it's not going to purchase at an excessive price, nor at an extremely low one either, so it's safe to state that it's a relatively safe period. However, DCA isn't a panacea like the OP is claiming, and someone who's not financially well-off cannot acquire Bitcoin, no matter the technique. Purchasing $20 per month, as some users are suggesting, isn't enough and won't cut it, even on a long-term basis.
The points you said are good in this case but I definitely disagree with what you said, indeed when talking about the quality of purchase about $20 will feel small but when the strategy in terms of quantity and effectiveness it is better. Indeed, we know that when we are in bitcoin with a small amount, it will definitely make a small profit too but the point is not there because in this case we must be aware that whatever amount we get in the end will be much better than nothing so that regardless of the amount that exists and we invest in the end as long as we have a level of consistency in making investments it will definitely be paid according to what we sowed before.
The DCA method is a good method if indeed we want to become an investor, especially in bitcoin with a long term especially if we are serious about doing it.
I don't doubt the significance of investing, through DCA or not, even in small amounts. Not everyone is comfortable investing higher amounts of money or can afford to do that. Personally, I don't. However, we need to set realistic expectations, not only for minor investments but in general. There are some users that are advising newbies to start even as small as $20 to $30 per month, which I'm not against, of course, but at the same time are laying completely unrealistic expectations due to the upcoming halving. $30 per month is $360 per year, which for the majority of us is a petty amount, and it's certainly not enough to make you well-off, despite what happens after the halving cycle is complete.
As I mentioned earlier, I'm not against investing small amounts of money; it's still better than not investing at all, while it also teaches the basic principles of saving and putting aside money for the future. However, this results in making Bitcoin look like a get-rich-quick scheme, which it is not. The media is also assisting in that due to a number of success stories from the early days or by altcoins such as Doge (the Elon Musk incident a few years ago).