Personally, I do not like ideas of "going all in" to investments...
To me, it sounds like gambling and or trading rather than investing.
Even though I get the idea that reserve funds can be saved up in order to have extra cash that goes beyond regular DCA buying to be able to inject into your BTC investment at various points along the way, especially at various dippening points.
You are right but investment is now the only way to be profitable for everyone, trading or gambling without experience is not very profitable, if one invests in Bitcoin now, it is almost certain that he will be in a profitable position within a few months.
Also as per your suggestion if one trades and gambles intelligently then more profit is possible, but most of the wise people can't do these things by following the right rules.
Even if someone started investing $100 per week into BTC near the top of the first 2021 peak and through the second 2021 peak, and he continued to invest consistently and persistently that $100 every week for the past 3 years, he would be profitable right now since he would have had invested right around $15,700 and he would have 0.558 BTC (which would be worth around $22,320), and personally, I think that would be a great place to be for a person with that level of a discretionary/disposable budget..