The treaty essentially states that only 5 countries (US, UK, France, China, Russia) can have nuclear weapons. India says this is discriminatory: either all countries denuclearize or other countries can develop nuclear weapons.
afaik india has a good record of preserving its nuclear secrets, and not doing "proliferation" to other countries.
Of course, such policies can be changed whenever India would want to.
Part of the treaty is that those 5 are supposed to (gradually) denuclearise, and also to assist with civilian power efforts.
and how is that going for the big players since the treaty was singed ?
As much as I would like nuclear weapons gone, I don't see it as being done to a satisfactory level that assuages India's concerns. I don't think anyone has made a real commitment to denuclearizing, akin to what South Africa did a while ago.