A long-term investment of 4 years to 15 years or more, an investor is not boarded about how the market goes either up or down,all he his focused on is how to buy more Bitcoin into his portfolio that will be beneficial to him in future .
You don't really have to wait for the dip before you invest more, just keep buying and accumulating in respective of how much Bitcoin is, and when the dip comes ,it gives you the opportunity to buy more and aggressively if you have reasonable amount of cash with you, it is not adviceable to wait for the dip, continuous investment is the best and the wright thing to do.
With people who join Bitcoin market and are in their first year in this market, going through one full market cycle that last about 4 years is already a long time. I believe that the Bitcoin market is volatile and wild enough to fear many newbies and no matter how confident they are at beginnings of their investment adventures here, first months inside this market would be very fearful and uncertain for most of them.
One market cycle is stressful with a lot of market fud news, and regulatory news and policy changes from governments globally. It is especially uncertain and more stressful in bearish months so before experiencing four years in this market, a full market cycle, there is not enough market tests from price to psychology on newbie investors here.
Before going through and surviving in all phases of a psychological market cycle, you are still a newbie here.
Actually, newbies will always be scared of their investments when it starts experiencing the real volatility that brings about the ups and down movements but it only makes those newbies become stronger because after they have experienced all these fluctuations they now begin to understand how the market works which can make them become stronger to finish a whole circle without thinking of selling their Bitcoins. Of course, one market cycle is 4 years, it will be so stressful for a newbie as they will think it's a lot of time but by then their portfolio might have started becoming huge already depending on the amount they have DCA in those years.