Bitcoin still got demand even its not too big, but most of the people still believe in bitcoin rather than alt coin, if you see clearly the demand of alt is lower than btc, the one that make alt coin got bigger demand because there are whales behind it, and bitcoin still become the core of crypto
It's not that people believe or do not believe in bitcoin. Most of them do not know the mechanism of its extraction and existence, so they can not believe or not believe in it. They previously simply hoped that bitcoin, as before, would grow in price and bring profit to them. That's the whole belief in bitcoin. If they see that bitcoin for some reason can not make a profit for them, they can easily switch to another crypto currency and will "believe" in it if it is capable of making a profit.