Does creating a file containing all emails from various leaks is sellable ? Even if the leaks are popular ?
The work is bassically to parse data, and then make data no redundant. e.g: a mail list ready to use
Does this kind of sale happen ?

Some people sell "leads" which are curated emails pertaining to certain types of users (crypto users for example). How well they actually sell is beyond me, and simply ripping out users from public databases is often useless. It only sells most times if they are private lists.

Per our rules you would need to disclose usage of any public info in your data

How can I get  a  "Selling"  Tag  on a thread like this mate::  https://breached.to/Thread-hbL-Meta-Domain-for-Sale

I wouldn't purchase a mix of leaked information. Who knows if that information is even real.