I would group those people in with creators who think that copyright means they'll earn more money. That is, people who are swayed by arguments appealing to the "common sense" that "artists should make money off their work" without specific evidence in support of their views.
Since copyright can be used to prevent content creation (for example, cover performances, sequel novels written by other people or derivative works) it isn't at all obvious that copyright leads to more content. The internet has led to more music and better music being made, according to the recent study I saw comparing radio play of new music over time. Webcomics make most of their money selling books of comics available for free on the web. For most of human history we functioned under a deliver-first, pay-later or -indirectly method of exchange; the internet has allowed this model to scale almost without limit for goods with zero marginal cost.
Since copyright can be used to prevent content creation (for example, cover performances, sequel novels written by other people or derivative works) it isn't at all obvious that copyright leads to more content. The internet has led to more music and better music being made, according to the recent study I saw comparing radio play of new music over time. Webcomics make most of their money selling books of comics available for free on the web. For most of human history we functioned under a deliver-first, pay-later or -indirectly method of exchange; the internet has allowed this model to scale almost without limit for goods with zero marginal cost.