No, it's not strictly voluntary, because the existence of a market sets a price for a product, and materially differing from that price either puts you at a disadvantage (deprives you of voluntary trading partners) or creates opportunities for arbitrage (disadvantaging those who would otherwise voluntarily trade exclusively with you). And if your competitor has a massive pre-existing wealth advantage, they'll happily eat the loss and undercut you until you're out of business. This produces worse outcomes in the long run.