Step 2: Prevent bots from signing in. (You really don’t want to miss this step, otherwise you’re free real estate.)
Step 3: Write your own bots that will scrape other “social” websites for content. This is to attract people before original content begins to form.
Step 4: Sell post priority and upvotes. And there you have it. Your own money generating cesspool of gradual deterioration.
That’s it. And yes… Easier said than done. Step 2 is really the hardest one. Perhaps make it obligatory to sign in with a phone number or something, cause capchas are a whole battlefield in itself. I don’t really know how hard / easy it is to get a bunch of phone numbers to use for this purpose…