This is a classic mistake. We have no way of estimating the future value of a given book. It's perceived current value (a large part of which is simply obscurity) may be low. But it's future value - to historians, ethnographers, to researchers seeking a specific fact or example of language use or a hundred other things - is literally inestimable.

To take a crude example in a different medium - new york in the 90s - widely documented right? Yet, if you want to find high definition video of street life in a given burrough on a given day or year, you're faced with an enormously difficult task. There were some HD test videos done in Manhattan in the late 90s (which have been posted to Hackernews before), but there's no equivalent for the other burroughs. Your best best would be finding original negative out takes or location scouting footage from feature films, a very hard task. That's only 30 years ago. Outside of the focal points of the worlds attention - English language, rich countries, places in the news, contemporaneous sources for 'non notable' events (lifestyle, how people spoke dressed etc) is surprisingly poorly preserved.

Hopefully you can infer how this tracks to the written world and primary sources for language, technical manuals etc etc.