The "only" think Reddit has is an engine to sustainably produce new communities as good as the original Reddit, at the cost of providing a pile of chaff I dislike that thousands of people enjoy?
Same thing with matter/antimatter, and "white flight" demographics. Also, the more energy-efficient we make our technology, the more energy we will use in total.
Any tension not in a buffered solution will collapse to dominance by one-side.
This one, though:
> Why can’t everyone just agree to a family-friendly, 40-hour workweek?
You can choose to opt-out of the rat race, and still be happy.
Some other too. Yes, to a first approximation, there are no easy problems (or free lunches), so only attack problems you'd love to solve.