Let me tell you the truth about how India wasted all that money on this project. The diameter of this submarine, like the INS Arihant, is 10 feet, which can only fit the tiny K-15 missile. However, the K-4 missile has a length of 12 feet, so it won't fit.
In a normal country, they would stop producing this class of subs and start building larger ones with a bigger diameter. However, since no other country will sell nuclear subs to India, India has to make them itself. The problem is that to do this, you need a huge steel plate bending machine. For a 10-foot diameter, you need a roller that can handle 17 feet, as the total should be 33 feet, with half being about 17 feet. To make a 12-foot diameter, you need a machine that can handle about 19 feet. India doesn't have such a huge steel plate bending machine, so they can't make it. But instead of stopping, India continued to spend more money on it. A member of the Indian parliament suggested that since the sub can only carry six K-15 missiles, why not add more? So, they decided to add a 10-meter section in the middle of the submarine to make room for more missiles. However, they didn’t consider that the problem isn’t how many K-15s you have, but that you can’t fit larger missiles like the K-4 in it, since the diameter remains the same. Adding more K-15s doesn't change anything. No other nuclear country will let your sub get within 750 km of it. But India keeps spending (wasting) more money on this, so after this one, four more subs of this class (named S4, S5, etc.) will be built. Well, it's your money; waste as much as you like.
