Many decades ago, when I first started reloading, reading through a Dean Grenell edition of "ABC's of Reloading", Dean showed his coffee can of spent primers and mused about what to do with them.
So....I started keeping mine. Was easy to accumulate the first coffee can as I was shooting a lot of trap and shotgun primers are large! Haven't shot trap for years and the second coffee can is taking decades to complete.
I look at this two ways: the first is look at all the reloading I've done and boy, was it worth it to spend all this money on all of this equipment. The second is look at all the reloading I've done and was it worth it to spend all this money on all this equipment! Yes, it was!