I don't buy it. We have two rovers on Mars right now, correct? They've exceeded expectations by operating for years, rather than the original 90 days expected, and for much cheaper than what it would have cost to send three, four, or five people there. And the cost doesn't even take into consideration the economic toll, but also the personal and psychological toll on the astronauts.
And they've only scratched the surface. Literally. If we want to find water, we have to dig many meters deep. If we want to find fossils of past life, we have to take deep cores, or have a paleontologist climb halfway up a cliff face with a hammer and a brush.