The opportunity to buy wisely, of course, when prices fall. Yes, sometimes the moment is missed for us because we don't have the funds available to buy at a sudden drop in price. At the same time we only make purchases according to the planning in the Strategy stage that we do with DCA. In fact, of course it makes sense if we make a trade that buys when the price goes down and takes profit when the price goes up, but this pattern is only to be played for the short term, not the long term. Like what you have done where you have held BTC from 2013 until now.
For a long-term goal, you simply buy and hold regardless of any market fluctuations, and if you want to buy on dips and sell on pamps, then this will be trading. If you want, you can try how well you can do it, but for this you must have a separate budget, which you should not mix with your main long-term investment.
If you have such a desire, you can simply check for yourself the statement that hold always wins over trading. I think that's how it works for most people.