See, the OP had carefully selected the 5-year period. Why not 6-years? Back in 2015, Bitcoin had reached an all time low of around $180 per coin, after crashing from $1,130 per coin in December 2013. Those who made their investments in 2013 were at a loss of more than 85%. And I personally know a few people who made their investment in 2017 December, when we had the ATH. Even now, those investors are at 45% loss.
Seems to me that the idea of this whole topic revolves around investing a dollar a day - or at least regularly buying BTC at no matter what the BTC price... which is a form of dollar cost averaging buying.
Of course, if you selectively pick a period and you lump sum invest in BTC at the top of the BTC and then you do not invest in BTC again, then it is going to take way more time for your BTC investment to get back into the black - however, DCA investing can be shown to be profitable, even if you had started investing at the top of BTC's historical price.
Look at this DCA website to see that the longer the period showing a three year investment in BTC as compared to gold and Dow Jones Industrial average. You can play around with the time settings at such linked website and verify that historically the more your BTC portfolio will be in profits in terms of the greater the amount of time that you had been invested in BTC.
Of course, past BTC price performance does not guarantee future BTC price performance results, but really we do not have any kind of meaningful evidence now in existence to show that BTC is lessening in terms of potentially serving as an ongoing good investment in current times and into the future. Furthermore, current BTC prices seem to continue to show ongoing asymmetric betting on BTC in comparison to any other asset classes - whether we are comparing BTC's current position and fundamentals to traditional asset classes or to various shitcoins.
In other words, bitcoin remains the likely ongoing leader in terms of any asset class that any person (whether normie, poor person, institution or even government) should be motivated to invest into using dollar cost averaging principles and practices so long as their investment timeline is 4 years or greater, and of course, the longer the investment timeline, the more likely that the employment of DCA principles and practices and solid ongoing accumulation of BTC along the way is likely to show profits and even decent likelihood of prosperity (of course, no guarantees with any investment that anyone chooses to make).
So part of the point that seems to be argued in this thread (and through OP) is to consider the BTC investment thesis in terms of DCA practices and principles rather than lump-sum investing and attempting to time the market and in your example situations that you argue, in which the lump sum investing at the top of the BTC price ends up in a long period of the BTC portfolio being in the red - which circumstances seem to be the exception rather than the rule in BTC that historical analysis of the BTC price performance shows - would have largely resolved that being in the red situation through an ongoing DCA approach.
