To put that in perspective, if Flipkart has sales of $100M every day of the year, at $36.5 billion, it would be half of Amazon's e-commerce revenue of $67.9 billion [0].
I think you are looking at it from the economy perspective at current time. But in the long term, Indian market is going to grow and others are not going to grow at similar pace.
The magic is in compound interest.
also, Amazon is available in lot of countries, whereas Flipkart is essentially India only. Over that, there is the currency and per capita differences.