In the end, it seems that amongst the most reasonable and prudent of planners, would not overly lump sum at the top, yet if they were to make such an error, then (absent some rare surprise/emergency exceptions) they should be more than ready, willing and/or able to continue buying BTC if the BTC price drops after the lump sum investment and especially if such dip lasts a long time and/or dips in considerably large kinds of ways. Personally, I don't give much of a pass or have a lot of sympathy for the lump summers who are not ready, willing and able to follow up with further BTC buys.. and if they have blown their whole wadd, then they are likely guilty of gambling rather than investing, which sure they are free to do what they like, but I am also free to not have much sympathy for such an approach to BTC.
In such scenario the best and the right thing to do is to keep buying, even when the price continues to go down , aslong is bitcoin even though it may takes years for it to recover one thing for sure base one his past performance it will surely come back stronger. When one continues to buy is not only increasing his stashes of bitcoin in a nice rate but at same time minimising losses because at that time you will be using DCAing to be purchasing bitcoin at different price interval. And not only that it will also increase the chances of making a bigger and better profit in a long run . And for those with goals as the price continue to drop it will also increase the chances of you getting to your target goal or accumulating goal faster .