If everyone hold bitcoin for 10 years and start to cash out a little bit since the 11th year, the bitcoin value will rise forever, this is guaranteed by bitcoin's design

There is an academic understanding that fiat money's value is decided by its usage, that is because it has almost zero production cost and forced adoption. However, gold and bitcoin's value does not come from transaction usage, they are mostly decided by the demand of storing value and current production cost

In fact, holding will reduce the coin supply on market in a most significant way, while spending will only reduce the coin supply on market for a while (when coins are in the move, they are not available for purchase/spending). Holding 10 bitcoin is equal to spending 10 bitcoin every hour (suppose the transaction take 1 hour to confirm). The only thing that spending does is to increase the awareness of bitcoin, but you don't really need to make advertisement for something that have true value, you hide it instead, wise people will find it by themselves