I doubt it is easy to find out the actual bottom of the price before a pump, but I would still say buying every dip is totally worth it if you are planning to hold long term. Buy the dip, or you might regret not doing it. If it dips even further, then buy more if you can afford to invest and it will bring down your average buy price. As long as you aren't selling cheaper than your buying price, you won't be making loss even if the price falls. You still hold the same number of coins. But it's a whole different story if you aren't planning to hold long term and wish to make some quick profit.