you're giving bad examples here. they all take way more effort than liking an instagram pic and you don't consider the "for the lols" factor.
people live boring, mundane lives. they're more inclined to do something that gives them even a shred of enjoyment, especially the less effort it takes.
i'm sure you know part of the reason for things to go viral in general, is the idea of being part of a group/community (here, the "egg-liker"), so i'll spare you that explanation.
the people that care about the things you listed already don't do them. so what you want, is for more ppl to care about issues that don't affect them directly or that they don't see as a problem. sorry bud, that's not how human nature works. we're inherently self-involved.
and of course it'll be forgotten soon, being remembered is neither part of it's purpose nor function. it's really just for the short grin when you click the button - "free serotonin, yay!" - that's all.