Observation: It is silly, but when BTC is hot, everyone rushes to buy it, when the price is high. When the price of BTC (and other cryptocoins) is low, it is a better time. Dollar-cost averaging lowers the risk of major losses, at least for those of us who are in it for the long term.
I found this informative article on dollar-cost averaging: https://www.investopedia.com/terms/d/dollarcostaveraging.asp