Actually, every time can be a good moment to buy ETH, by average. Moreover when we buy it by understanding what we are supposed to do next.
I mean that we exactly know the purpose of buying ETH or BTC itself, for short term or long term.
And every time the price dropped like now is actually a good moment to buy BTC (once more by average because we will not know later will be dipping again or not).
Sometimes, people are more desired to buy BTC and ETH when the price is very high when the hype of the crypto is very high. But when the market crashed like what happen right now, they are too afraid to buy again.