I think those who trade in Bitcoin have less profit but also less risk. If you think it is risky to invest in Bitcoin then I think you are wrong because people have never lost money by investing in Bitcoin, but they have gained a lot. But short term investment can never make much profit, so long term planning is the best and best investment. An experienced investor never invests short term, but he plans well and thinks about long term investment and uses DCA method. Be sure to buy deep when you invest in Bitcoin, and if you're by using the DCA method, you will reduce your risk of loss somewhat. If you follow the methods of investing monthly or weekly using the DCA method, you can expect to be risk-free. However, one should not think of selling Bitcoin when it is invested, but rather holding it until such time as the market does not generate new ATH. However, when the Bitcoin market forms a new ATH, you should sell the Bitcoins you have invested. Although we should always think positive, Bitcoin investment is best for long term, so it is better to invest and hodl Bitcoin for long term.
Also you claim people never lost when investing in bitcoin, and this cannot be true, investing in bitcoin, as solid as I believe bitcoin to be, still contains an inherent risk, and you could be forced by circumstances to sell your bitcoin for a bad price even if you do not want to.
Finally you claim DCA to be risk-free, which again is not possible, as even something as simple as getting out of bed has a risk, so DCA must have it too, even if it is a very solid strategy to use by newbies and experts alike.
Concerning this your first paragraph here, it's actually true that their is a risk attached to Bitcoin investment just as every other investment, but concerning those people that got some losses in their Bitcoin investment, it's was due to lack of planning, lack of source of income and an emergency funds, that is the main reason someone will be compelled to sell at a loss, if not, I am very much positive that no long term investor will sell at a loss, because the probability of Bitcoin doubling or tripling it current price in 10 to 15 years time from now is very much higher, compared to Bitcoin going back to 5 or 10k.
And as for your second paragraph, I don't really believe that their is any flaws in the DCA accumulating strategy, because it makes you accumulate Bitcoin on your own convenient terms, it can only be flaws if you decide to be super aggressive, and it's start affect your ability to afford your daily financial needs, apart from that, I don't see any flaws in the DCA accumulating strategy.