I think not knowing "when" is one thing, but knowing "if" is the important part. I personally "know" that it will go up, don't know when it will go up but I know it will, which is the only thing that I care about and that's why I buy bitcoin as much as I possibly can. That's an important part of bitcoin accumulation that everyone should be aware of.
Obviously just because we are not buying it right now doesn't mean we are too late, if you are not buying right now, then you can buy tomorrow and still profit eventually. So, always be on the look out to buy more and invest more, because no matter when it goes up, it will eventually happen and give you more profit.
This is a nice way to put it, traders spend their time trying to figure out when the next big movement is coming in order to maximize their profits, but this is not the question investors should ask themselves, what they need to ask is if it is possible at all that an asset reaches a specific price, and if they believe this is the case then the only thing they need to do is to buy that asset, hold it and enjoy their profits once that asset finally reaches their target price.
I think it is not even a specific price but more like if it will go towards the direction I want it to go. I am a long term investor with just a side of trading a bit, and I can tell you that the mindset is very different. When trading I have a price to buy if it goes down there, and a price to sell when it goes up there, and I react depending on how it moves.
However, when I am holding, as long as it is going up eventually, which I think bitcoin and ethereum does, then I have nothing else to worry about, it can reach any price it wants, the price is not what I wonder, it is about the direction which is up. That type of difference is very different parts of the brain, and you need to realize how you can separate the two from each other.