well opposing copyright isn't thievery, for a start. theft is the act of taking something without returning it, removing the original. digital information can be infinitely and perfectly copied.

copyright enforcement is instead about giving certain parties exclusive monopolies on the spread of information. this gatekeeps culture and stifles free expression. in return for what? trying to sell access?

note also this monopoly is only enforced via the threat of state violence.

tangentially, there's also the fundamental inversion of value that occurs when artists try to fund themselves by selling art as if it were a commodity. the value in art is not necessarily in the final product alone but moreso in the creation of it. 

copyright asks us to perform creative labour for free, and hope to recoup our losses via the market (in which you must differentiate yourself from millions of functionally equivalent forms of art and entertainment -- good luck!)

when you recognize this inversion of value, you recognize that the real answer to making sure artists get paid is to actually pay them for the work they do, not to commodify what they produce. things like commissions, patronage, public works funds, etc. all get to the root and heart of the issue.

copyright is in effect more akin to theft -- theft from the public, from the commons, from culture. it benefits no one except those who "own" a lot of art -- the disneys of the world.

in short: if you want artists to get paid, copyright is a really poor and ineffective way to do that. it just leads to big monopolies on art, at the expense of everyone else.