Are pre-launch discounts in Gurgaon just a myth?

Did a site visit to some projects near Dwarka Expressway, also checked out Gee Aar Realmart. I'm currently in a 2BHK but thinking of upgrading to a 3BHK for investment. Builders often push pre-launch offers, saying it's a huge discount. Kya yeh pre-launch pricing sach mein better hoti hai later buying se? Ya hidden costs baad mein sab nullify kar dete hain? How much can one realistically save on a ₹2Cr+ 3BHK through pre-launch in Gurgaon, especially from an investor's angle?