Information for non-commercial purposes should be free for general social enrichment. Information for commercial purposes should have some path towards monetization but the one we've got right now is clearly a terrible fit.

For the future, though, usually if you just email one of the paper author's with even a hint of interest you'll get the full paper and often a neat discussion about how your specific interest relates to the paper. I think people assume researchers get hounded by fans like celebrities but they're usually folks that love to talk about their topics of interest.

I don't know anyone who should be feeling guilty from using libgen in the first place.

I feel guilty for publishing in elsevier and paying for their “services”. By all means using scihub and libgen is morally superior position.

Well, isn't libgen no longer accepting uploads for years now? The last few years really haven't been great for shadow libraries which is incredibly unfortunate.

Why would you feel guilty. Its just information. Go get it.