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You deciding to sell might make some people think the coin is worthless (maybe they know you're a legislator who knows that the coin is going to be made illegal soon) but the other side of you deciding to sell is someone else deciding to buy.
I just provided examples for that. There are HODLers who don't care and DCA every week. There are speculators who sway easily. This creates asymmetry.
Therefore, you can't assume your decision to sell will have any more effect on the market than your trading partner's decision to buy does.
You seem to assume that information asymmetry doesn't exist. It does. Markets exists because of information asymmetry. If everyone had perfect information there would be no need for markets - resource allocation problem would be solved.