> when the op just says that basic sanitation should be prioritised over military helicopters.

Why can't a country do both? Most countries in the world are investing in military, space or other national security related projects. They all have some internal issues they are facing. It doesn't make sense to prioritize only one thing over the many issues a country faces.

Imagine how many toilets the cost of a single helicopter can buy :)

Clearly not both topics are given the same attention.

Because money is a finite resource. The budget has X Rupees and and Y topics to split them under, and any rupee spend on the military is one that isn't spent on toilets or schools or childcare.

Yes, but this is an allocation problem. Is it feasible for India to allocate 100% of its budget to toilets when it has border conflicts with its neighbors and terrorism around?

India has nukes, so they're undoubtedly overspending on defense.

Russia has nukes. Does it look like they are winning? Nukes are for last resort. No one is going to use nukes in limited conflicts.