Since bitcoin is not a ponzi scheme or any kind of fraudulent attempt, it basically can be bought anytime ^{[P2P or on any reputable exchange].} I don't think it will be a problem if you really want to keep those bitcoin as a long term investment.

Okay, buy dip and DCA, but actually these are some ways to get low price and collect more. I can buy for $20K, while I'm also willing to buy above. But remember, invest as much as you can afford to lose. This will help you think about it as simply as possible.