Many of us likely realize that the more BTC that we accumulate, then the less we might feel emotional about the BTC price going up and the possibility of our missing out because our own accumulation of BTC has already largely prepared us for UP, and so part of the trick for any lowcoiner or no coiner is to get to a stage in which s/he at least has enough of a BTC stash that s/he is already feeling financially and psychologically prepared for up, even if s/he might have had wanted to have more BTC, at least there is enough BTC in the stash that there are good feelings about the BTC price going up.
This is the reality of bitcoin holding for a long term that you just stated above. Buying in lump,wouldn't make you think much of the DCA strategy because you will relax for a while when your bitcoin has attain a significant figure or close to your target figure. But at the same time this strategy is for someone that do have once in a while some reason sum of money or for someone rich. Buying at dip is good when you prepare towards it,believing and hoping that bitcoin price will go dip because of its volatile in nature. This a good strategy because both the rich and average can take advantage of the market. Buying in lump and buying at dip will help one achieve his target amount of bitcoin fast than when you are using DCA method because one cash inflow might vary from time to time and when bitcoin price has pump to an extent,the funds for DCA would lesser fraction and the investor that is buying in lump or during the dip will just relax and keep holding till it is the right time for him to take advantage of the market again.
There should be some more savings if you really try to buy all at once without thinking about the price considering in this case of course we will also at least be tempted when we have bought at a certain price and bitcoin is declining again and is in a place that is indeed more worthy of buying.
Even though it's not wrong, but we have to have several pockets so that when bitcoin goes down we are ready to go back to netting at a price that we think is right. But indeed in this case DCA is clearly better in my opinion by not being too impulsive and buying as we have planned and at the amount we really want while waiting for some conditions and movement because if it goes deeper down then we can buy more than before .