Which altcoin do you think will be the next Bitcoin?
There is no coin that will take that place, no matter how hard they try. 
Just like when they think bitcoin will moon hard in 2017 when the price already has moon enough, they don't see the correction coming.
The people who were in the market for a long time and people who are aware of the financial market knew that the market will crash after a crazy bull run like that, it is not a big surprise and we will see those kind of bull runs in the future too, that is a speculative thought process because we may or might not see another crazy run like that, but one thing is certain, the price will rise eventually in the long term.