other way we can answer the detractors is by asking a simple question ...what has Mars mission done to Indian space science ?You are right in what you say but then one should remember the sole reason for ISRO's existence is not human spaceflight. They are working on many different missions at any one time.
has it cause damage to Indian space science or benefited it ?
why it has to be Zero sum game always ?
what is the proof that Mission to venus is going to eat up into budget of GSLV MK III and CE 25 ...
they are underway anyway ....
Some people like @he-man are hell bent to oppose for sake of opposing .