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.