Yes, waiting for a price drop when buying Bitcoin is not an appropriate strategy for long-term investors. Logically, we should understand that waiting for a price drop is a strategy that is prone to dilemmas. So, rather than worrying and missing out on opportunities, I don't think buying Bitcoin should be fixated on price. Regardless of the current price, it's highly likely that in 10 years, the price will be much higher, and we'll profit. So, why ignore momentum and choose the right price when buying Bitcoin?
There is nothing wrong to wait dips for purchasing bitcoin but experienced investors do it differently than newbies. Newbies wait for lower prices, try to find bottom prices to buy in, while experienced investors can do Dollar Cost Averaging regularly and don't mind about price, or they can wait for price dips of 10%, 20% or 30% and buy without concern about at what prices they make purchases.
They know that price dips are very good for accumulation and if they can hold bitcoin for a long time, profit is very good especially if they buy in dips.
Sitting idly and waiting for dips to happen before you buy Bitcoin is a bad practice that should be discouraged by all because it has made a lot of people to miss buying Bitcoin at decent prices instead jumped in when then felt price was leaving them behind with some ending up in problems. The only condition I will support someone keeping some funds for dips is when the person is using a hybrid system of DCA combined with buying the dips, This way you can keep the DCA ongoing while allocating some funds for buying the dips so that you will not miss your chances of getting Bitcoin at any market condition. Apart from this, I will always go with the DCA method which is easier to use for everyone.