This is not true. I currently live in a really nice apt that I rent. My landlord hasn’t substantially raised my rent in 3 years. I will eventually buy once I find something that motivates me but what actually empowers me to negotiate buying is that I’m content to walk away from the table. I don’t have to change my living conditions right now even if I would really like to.
If you aren't willing to leave, you aren't negotiating.