See, I'm old enough to remember this battle starting for music and movies. We know how that ended.
But now, it's for the very knowledge that drives our civilization.
"Stallman was right", oh how that statement is going to get tested.
1. Film and music were always vaguely reasonably priced, and collecting a fee is totally reasonable - at least some of the money goes to the creators. This is not true for papers. The authors are never paid and the prices are insane.
2. Music & videos are luxuries, and are also somewhat fungible. If you need a specific paper (e.g. because it was referenced by another) you usually can't just swap it for another.
3. The actual files are usually a lot smaller than music and definitely smaller than films, so it will be easier to share entire libraries and hence harder to stop.
4. Morality is clearly on the side of sci-hub. Music/film piracy is much more ambiguous.
Also, in wealth terms, if you start with the reasonable assumption that a pirated copy doesn't directly translate to a sales loss, then piracy can be argued to be a net plus, since vastly more people "profit" from it (the people who download) than there are people who suffer from it (the people being pirated).
Just wanted to mention those arguments, since I rarely hear them in these discussions.
I think the reasonable assumption is that it translates on average to a fraction of a sale loss; less than one, but more than zero.
The argument "I'm pirating the fruit of your work and investment against your will, but trust me it'll be in your best interest, I know your interest better than you do" is untenable.
Academic work also costs money, but journals have tricked someone else into paying for it. Research gets done on government, corporate, and university budgets, submitters get no compensation, and reviewers do the hard work behind publication for free. Journals have been priced far above costs for decades, but with the advent of online distribution costs have sunk even further while prices continue to rise.
The best (moral) argument against piracy was always "if everyone does this, we won't get more media". That's not even true in the case of journals: it looks an awful lot like the system would find a way to work even at 100% piracy rates.
0. A huge amount of this research is publicly funded, and access to results is something we've already paid for via taxes.
Extremely affordable all you can eat subscription models?