Different people have different strategies in terms of investment and everybody have a particular strategy that work for them.
Buying Bitcoin by DCA does not necessary mean that the investor have limited capital, most people that buy Bitcoin by DCA still have the capital for lump sum but one of the reason why some people prefer DCA to lump sum is that some people see lump sum as a method that is risky because of the volatile nature of Bitcoin which they cannot possible tell what the price may be in the future. So to avoid any uncertainty in regard to dip they see DCA as precautionary way of buying Bitcoin than lump sum which requires buying Bitcoin at once with the capital at hand without considering whether the price will dip or not.
The truth is that if an investor see's lump very risky because of the volatility of bitcoin I don't think the DCA method of investing will be seen in a different way because these are different strategies of investing but the same market. I do not agree with you why you think people don't prefer lump strategies because of the volatility of bitcoin, even in the DCA method volatility still happens. People just prefer to use DCA because it is straightforward and stress free. The most important aspect using the DCA method to invest is that you can be very consistent with your investment because you are just investing with amount you can afford, it doesn't matter what the amount is but the important thing is that one is investing with ease.
The value of investment lies in its long-term nature. If you think long-term, the volatility of Bitcoin has no impact at all. In long-term planning, a lump sum strategy requires more capital. Many people prefer investing in a lump sum strategy. Yes, with a lump sum strategy, you cannot enter the market at every moment, as you can with DCA (Dollar-Cost Averaging). If you consider the lump sum strategy risky because of market volatility, you're completely wrong. The price difference between Bitcoin today and in 10 years might be huge. For this reason, a $10k or $15k volatility doesn't matter.
You may prefer DCA because you can determine the amount of your investment according to your capacity, enter the market at any moment, and by investing small amounts, you can also build a larger portfolio. Due to the simplicity and stress-free nature of the DCA strategy, it's definitely something you can prefer. Personally, I also prefer DCA, but that doesn't mean I try to disprove other methods. If you think DCA is only for those who don't have significant capital or the ability to buy in large quantities, you're wrong. Many large companies (like MicroStrategy, Tesla, Block, and others) that don't have a shortage of capital also prefer and use DCA. Especially for a newcomer, it's advisable to manage investments through DCA at first. After gaining experience, one can adopt other strategies based on their personal preference.