Rebirth of a Protagonist who becomes a Villain

When an average White Collar worker gets Transmigrated into a generic Protagonist, see how he takes advantage of his foreknowledge and cliches to get whatever he desires. . After all, Cliches are famous because they are enjoyable, right? Well as long as you don't hold back and are not a dense protagonist anyways. . . . I am new to writing, and have written a BTTH fanfiction before which is on hiatus right now. Please bear with me. . One thing I would like to make clear from the start is that this is a Harem fic and will remain so. I see many people on different fictions that don't like romance or harem in an evil protagonist. Personally, I believe that there is no merit in reaching the summit of the world where you will remain alone for your infinite life. Hence please turn away if you don't like harem.