The point of this calculation
This is not an argument against spending money on things you enjoy. It is a way of seeing the true price of a habit you no longer notice — a subscription you stopped using, a daily expense that crept up, a recurring charge nobody reviews.
Three hundred rupees a day is nine thousand a month. Over twenty years, invested, that is a materially different retirement.
A more useful version of the same idea
Rather than cutting spending, redirect increases. When your income rises, route a fixed share of the increase into investments before adjusting your lifestyle to it. The money is never missed, because it was never in the household budget.
An annual step-up on an existing SIP achieves the same thing automatically.