I agree with buwaytrees here, it is usually a very easy thing to do. Some people have trouble with the whole long term holding things. I feel like it is the easiest way to make money, and it just feels like it is the opposite of hard, you literally do nothing while holding, holding is not a thing that you do, it is just the name we call to doing nothing.
There are some people who fail to do it, don't know why and how, but it just feels like they are not good at it at all. I have been doing DCA for a while as well, and I wish I started earlier, I would love to have a lot more right now, if I had money, I would buy bitcoin right now without a worry at all, it is as close to bottom as it gets anyway.
Holding is a simple task but I don't understand why it becomes difficult for so many people. They enter the market but don't do their research, they're only interested in the short term, not the long term or the money they are investing can be borrowed, so when bitcoin starts to drop 20%-50%, there is panic selling and panic selling increases after bitcoin plummets. If they invest with the idle money they have, maybe things will become easier.