Please take a moment to get my point before you conclude. I know a lot of people judge a post by the topic alone and if that is applied to mine, I might be sounding anti-bitcoin since selling is highly demonized by a lot of people in this community.
Nobody is demonizing selling bitcoin but the people n you are referring to believe that the price of bitcoin will continue to grow over a long period of time and which is very true.
Now the question is, assuming everyone who ever bough bitcoin is holding their bitcoin in their private wallets, what will be the fate of bitcoin and the bitcoin network? Does holding bitcoin strengthen the bitcoin network? If no, are those who sell and more their bitcoin on-chain generally doing bitcoin bad?
Do not forget there are traders also. This makes what you think not to be possiblenbeciase people will continue to buy and sell bitcoin. I think this answers your question. But if you hold bitcoin, you will later make money from it.