Waiting to buy Bitcoin at the right time is not a good idea, when do you know is the right time, saying we need to wait, it might be dangerous because you don't know when the price will come down, what if it goes up again and ondo we still keep waiting.
A long-term investor can't be waiting, he sees everytime as an opportunity to buy and hold since it will take him a long time to reach his target, and so he believes at any amount he buys he his going to make profit not loss.
There are actually exceptions to this. For example, it makes no sense to buy when the price starts to rise very quickly. In sudden rises, you can buy at the top and then see it retreat. Not getting caught up in FOMO is something that long term investors should also do. You create a strategy and you stick to it. That way you won't be affected by sudden price movements.
Long-term investors also aim to increase their coin holdings. If this gives them the opportunity to buy at a low price, they want to take it. Long-term investors usually don't get FOMO. They know that Bitcoin will rise and they strategize accordingly.