Wow a 15000BTC sale brings the price down for only several hundreds? Bullish!
In gloomy days like these, I try to imagine where the price will be in 3, 5, 10 years? There is no need to wreck my nerves by these short dips. If I just hold, I will become a millionaire way before my retirement. So, instead of selling, I prefer to buy moar bitcoins with my pathetic salary. Who knows, may be we will see new ATH sooner than expected. I don't want to be on the wrong side when this happens. Yes, I have faith that I will see it and enjoy it with my full stash intact by these shakeouts!!!
If you are willing to have a time preference horizon that goes beyond 5 years, it seems that you have really decent odds of profiting stupendously by continuing to dollar cost average into BTC until then - and hoping for the best - even if you happen to be regularly investing with a "pathetic salary," as you mentioned.
Of course, such hope regarding the future of BTC (and presumably BTC prices that will follow) is based on a certain kind of disparity of information in which you seem to understand the fundamentals of BTC and there are so many average Joes who either do not have a clue about BTC or they are filled with Angst or apathy regarding the extent to which bitcoin "may be valuable" (from their perspective).
On the other hand, if your time horizon is way shorter, then there certainly could be some unnecessary risks - for example even less than 3 years - and you would not want to put a great amount of your money into BTC if you really needed to have that money liquid in a shorter period of time - such as less than 3 years.