if no one spends any bitcoin it loses its value as a form of currency.it becomes a currency that doesnt transact.
Also if everyone just holds their bitcoin, this decreases the amount of bitcoins being sold to essentially 0,meaning the buy price would go up drastically, therefore increasing the value.
Literally that too only has the possibility to be happened. Because, all the people will not take one single decision of not spending. So, there would be some people who will be spending some bitcoin for their own reasons. So, the possibility of having some bitcoin movements across people will be occurring somewhere for sure. Due to less availability of bitcoins for buying, the value of bitcoin will skyrocket.Also if everyone just holds their bitcoin, this decreases the amount of bitcoins being sold to essentially 0,meaning the buy price would go up drastically, therefore increasing the value.