Have some doubt on it,
When Bitcoin rises, other coins fall because people are selling their alt coins to go into Bitcoin?
That's right, this is what makes Bitcoin domination increase,
because many people sell their altcoins and buy bitcoins when fomo like this comes,
this has become a cycle, when the price of Bitcoin goes up, altcoins go down, if bitcoin is sideways you can go to altcoins,
because the potential to go up is very high.