[edited out].
I have gone through the question you add above and I would rather be the guy who spent $28,500 and had somewhere between 27 BTC and 34 BTC (with an average cost per BTC between $838 and $1,056). Even though I ended up spending more money than the first guy in acquiring my bitcoin. I also ended up having more bitcoin in my possession which is much more profitable than the first guy. Although both of them are successful with their investments.
Each were able to invest according to their financial capabilities. My assertion in making the comparisons is that the first guy ONLY did a lump sum purchase of bitcoin with $5k and the second guy did the lump sum, yet continued to invest into bitcoin through out the period.
So my assertion is that the first guy purposefully chose to be less aggressive in his investment style than the second guy, and it seems that the first guy was more whimpy in his investment style than the second guy.
Sure, it was not guaranteed that all of the extra money that the second guy put into bitcoin over the next 9 years was going to end up paying off, and it cost him $50 per week to put in that extra money over 9 years, which I was presuming to be fairly easily within the means of either one of them to continue to buy bitcoin, yet the first one chose to limit his investment in bitcoin to the $5k amount.
With bitcoin we see that historically it had been the best of assets to invest in, and right now we are faced with similar kinds of choices, and we cannot know for sure whether our choices to ongoing invest into bitcoin are going to end up paying off.
Well for me I think the risk was worth taking. It is better to invest now and find out what the outcome will be in the future than to neglect investing at all, while figuring what the future will be like for bitcoin. If it eventually pay off the person that decided to invest will be considered as a wise person. If it doesn't pay off by that time, we continue holding with the hope that it will pay off someday.
From your example it was evident enough that lump summing once without following up with DCA during the waiting period is not actually a wise decision. While waiting for the x number of years, one should take the advantage of following up the investment, provided that the investor has the means. Even if it wasn't guaranteed that the extra money the investor is putting is not going to pay off in the end. It was an avenue for the second guy to save up his money by investing it in bitcoin through the DCA of $50 per week. It was a risk that was worth it. It was better than the first guy who probably was saving his extra money he was getting in Fiat within that 9 years intervals.