If bitcoin rose to 1M I would sell all my bitcoin and invest in buying an house cause buying an house takes away some monthly costs which allow me to save more money and invest more money.
I would keep investing in bitcoin still.
I also will do the same but not the part of selling all my bitcoins. Maybe I prefer to sell only less than 50% of my total bitcoin savings. I never interested to come out of bitcoin savings at any point of time also for any value of bitcoin. Because I'm strongly believing in to bitcoins that it will keep on increasing in value over time.
Similarly I also will keep on buying bitcoin continuously regardless of what value it will be having. So, that I will be keeping on myself into bitcoins value appreciation race.