> Nothing is saved overall.

This is not true. You're missing that, if there is no second-hand market, phones get an early, premature grave, meaning more e-waste.

Imagine there are 10 million people in the world and they all want a phone. 1 million neophiles only ever want the latest phone, released yearly. The other 9 million are luddites who are OK with a second-hand phone. All phones last exactly 10 years before failing, and never become obsolete or damaged.

No second-hand market allowed: 1.9m phones sold per year, 1.9m discarded.

Neophiles buy and discard 1m phones (into the dump with 9 years of life left). Luddites buy and discard 900,000 phones (they have no second-hand market to buy from, so they buy new phones, but they use them for full 10 years instead of just 1, so the 9 million only buy/discard 900,000 phones per year on average).

Second-hand market allowed: 1m phones sold per year, 1m discarded. 900,000 less!

Neophiles buy 1m new phones but sell their old phones to luddites, discarding none. Luddites then use them for 9 more years before discarding. There are 9 million luddites with 9 years of phone use meaning they need an average of 1m second-hand phones per year, which happens to be how many are on the market thanks to the neophiles.