Bitcoin has been having such corrections since inception and so it will reach $1million the same way it reached $72000.
It's quite normal for any asset to have dips/corrections and bitcoin being more volatile is prone to having such dips.
There’s no problem with dips and corrections as they occur normally in a highly volatile market as well as bitcoin, the important thing is there’s always a price hike after that. That means that regardless of the time, bitcoin will still be able to achieve $1 million throughout the process, we just cannot tell when it’s going to happen.