My reasons? (I scan for Kiwi's World)
1 - partly nostalgia. I love to read old magazines, so I also appreciate the work others do. Because I can reciprocate, I do.
2 - I've been a gamer since the late 1970s. I've been saving all the magazines I've bought since the mid 80s. I've come to the point where I needed to empty out the literally hundreds of kg of magazines filling my cupboards. I couldn't bear to throw them out with at least seeing them preserved so I can read them on a tablet, and shared for others to enjoy. I'm keeping some treasured stuff like a Zzap 64 collection but most is going.
3 - I keep my workflows pretty simple and I have a document scanner which can feed 50 sheets, so I usually just scan something while watching TV or browse Reddit or whatever on the other monitor, so it's something I can do without concentrating too much
I hope that others enjoy the stuff I do but thats just a side benefit.