If you are having a long-term mindset then no strategy is to be regarded as useless because you have time to grow your investments over time. It all depends, according to your financial power which gives you the leverage to take decisions that aligns with your sole aim and investment plans either DCAing, ump-suming, buying during dip are all good strategies.
A man's financial situation does not always help him to think right. Humans are profit-hungry creatures. People always try to get more profit in less time or not? So many bug people want to do DCA, but don't have the humanity to prolong it. Because of this they often forget simple methods like DCA and focus on other difficult/businesses and end up losing money.
If you want to be a real investor, you should not invest in a large portfolio at once. You need to invest a sum which, if lost, will not disrupt your livelihood.
That is, you can invest the rest of your living expenses with an extra fund. The DCA method also says the same. You invest fixed amount every week or every month i.e. at a fixed time based on your income. If you make this investment for 5 years and longer, you will have a nice and big bitcoin portfolio.