I concur
Do the maths (or math for our US friends): which is the most cost effective per dollar in terms of the science return, manned or robotic missions? The answer is WAY biased towards non-manned for the reasons that this geezer mentioned. $100b for the ISS to do what exactly? How many mars missions could one fund with the same budget? How many Hubbles could we launch?
It's noticeable that the main advocates for manned missions are politicians and ex-astronauts, not the scientists. We hear nice soundbites of "reaching for the stars" and so on, but the reality is we are stuck here on terra firma. To reach the moon and pick up a few rocks would apparently cost the entire NASA, ESA and chinese space budgets for the foreseeable future. To establish a manned base with a view to mining the moons resources would cost more than all the above combined several times over. To reach Mars would cost a sizeable fraction of the planets GDP.
Manned missions are more expensive due to the fact that they ARE manned. Space is dangerous - losing a robotic mission is a matter of money and some grief for the engineers and scientists involved, losing an astronaut is much more serious.