You can't decide that whether it's the highest point or lowest but you should be having satisfactory returns instead of regretting later on.Suppose you invested in around $30k and when prices went to $50k also you have made profits so you need to decide to sell or to hold as it could go above or down after that.But when it's dipping people start panicking as if it was supposed to always rise and we can't change this.So best is to make your decisions.
And there are people who see it at 30k, and go "maybe it will go to 25k, I will wait some more" and then they regret it when it is 50k. Those people are the main reason why we are not high right now you know that right? If all of those people got together and bought right now, price would be 50k anyway. So these people who are waiting for it to go down, are the same people who end up missing out so much of crypto as well.
I believe that bitcoin and all other coins would be better off if people had a little bit more trust to it. Maybe it wouldn't be that great for everyone involved and some may lose some, but it would be totally great if everyone invested into it.