Of course, if it is possible to hold Bitcoin in the long term, then such investment strategies must be adopted. Investments are usually only profitable if they are long-term, but investing with a small amount of money can be done long-term only by following the DCA method.
Buddy you might be having some misconceptions about investment but investments are not "only" profitable in long term, short term investments too are profitable but you can't obviously look into that as an option in bitcoin because we consider with as wagering or gambling but which is more important to shitcoiners because they can't obviously hold those coins for long term.
when we say long term, we should be able to state out what we mean by long term and extablish the reason why we're considering investing for the long term. We've used the term long term investment so much that a lot of people are begining to assume that once you've invested for the long term you're bent on being profitable with your investment. In reality, it's not how long one holds his Bitcoin that matters, for as long as you care, you can choose to HODL $500 worth of Bitcoin for 20 years and look at it as a long term holding and won't be half as profitable as one that holds $20k worth of Bitcoin in less than 5 years. While talking about long term investment it's best we also relate it to the essence of making the investment for the long term. If you're just investing for the long term and you're careless with how much you're able to accumulate within such timeframe, then your long term investment wouldn't make any difference.
Building a portfolio with a long term plan in mind gives you an opportunity to to build a resource that guarantees long term investment and when you have a good plan in place and follow it out to the latter, it's going to make a huge difference in terms of how much you're able to build your portfolio at such period of time.