You don't seem to be saying anything different than me in terms the unlikelihood that someone would buy a whole BTC at once, and even an aggressive DCA strategy in the ballpark of $100 per week is going to take 6 years just to invest up to $31k, so it may well not even be fast enough to get 1 BTC in 10 years at that $100 per week level of DCA...
But yeah there are some people who can be more aggressive than that.. but usually not regular folks.
Sometimes $100 a week is too heavy for the regular person and even more so if they live in a country that has lower wages compared to other countries. Moreover, for those who are young and don't have a permanent job, of course they might not be too focused on investing $100 every week in Bitcoin. But time is not a problem in long-term investing because time passes so quickly and the $10 or $20 they invest regularly will not feel they can reach 1 BTC someday.
I think in long term investments we don't have to check price to stabilize our purchases, I mean the price today will be different in the next day. So buying regularly and not caring about the price will give you the perception of accumulating Bitcoin regardless of the current Bitcoin price. We only focus on 0.1 0.2 and so on until we reach 1 BTC in our last stage. 10 years or 20 years is quite a long time if you imagine it, but if we take it easy in investing, of course time will pass very quickly.