Although, no investors is happy when his investment is declining instead of appreciating but a good investor that have good understanding of the volatility nature of Bitcoin will not be under pressure when Bitcoin is in dip because the rate at which Bitcoin appreciate is much more than the the decline. And this is the reason why planing for long term investment is one of the unique quality of a good investor because if you hold a starch of Bitcoin for long term you will surely recover all the lost incur during the dip and still maximum your profit in the future.
Irrespective of any circumstances a good investor is always patience and perseverance and will always tend to sustain his investment for long term.
First of all, whoever that is not happy when the price of Bitcoin is falling cannot be said to be an investor but a trader who buys with the idea that the price will rise for him to sell and get some profits but let's us also look at it this way, even if a trader buys and expect the price to rise for him to sell, after selling won't he also wait for the price to fall before buying back again? This is where volatility comes to play which tends to push the price forwards and backwards. Investors care about market volatility more during DIPs periods because they will buy and hodl at cheap prices which will enable them maximize their profits as against when their investment will be due to sell in the long term. No level of DIP scares an investor with plans of a long term investment because he is confident that the price will still rise again, it will only take some time.