Here is a straightforward reason that no one who claims to be some sort of economist (social or otherwise) can argue against: India has 1.2 billion people and is not particularly endowed with wealth that it can dig out of the ground. So the only way to create wealth is to turn 'sand-into-silicon' aka make productivity gains using the only abundant resource it has - the human resource. Now if this particular mission can inspire .0001% of additional population to aspire for non-manual labor employment (i.e. study STEM etc), the productivity gain from those people will pay for this mission many times over (I haven't cared to do the math here because I just want to illustrate what I thought is an obvious point which people somehow gloss over).