What you generally explained about supply and demand is obvious but what you followed it up with makes little sense because when you say "sellers", you aren't talking about a single entity that works as a single body. You are talking about many individuals that are naturally making decisions based on market dynamics, their financial situation, their speculation, news, emotions, etc.

Your statement only makes sense if you want to suggest that through "market manipulation" we should do something to influence the market participants to sell less and create artificial "scarcity".
Well, that is not an easy thing to do in Bitcoin Market any more...