It's the opposite of the mantra "buy low, sell high".
That is exactly it, now is the time you should be buying if you intend to build a larger position. Buying all the way down the dips will give you a better average entry price. Don't try and guess what the low will be, just buy little by little everytime it goes down further otherwise it may reverse on you and you'll miss the opportunity altogether. That's not a trading strategy, but it is how to accumulate a hodl.