I don't disagree that the problems are hard, but I think reality will show people where they need to be. No one is going to spend tens of billion dollars on a trip to Mars unless they really think it can be done and have something to back that up.
I think it is possible to set up a colony now, it is just extremely likely to fail with the shoestring funds and priority we're allocating to it. I think that any one of a million things can go wrong that would kill every last person who tried to do it. So yeah, Mars One = space suicide pact. That is, if it even gets more than a foot off the ground.
What I don't think is that we lack the suitable technological level or resources to do it. We don't need to have another technological revolution to make the trip possible, we just have to devote the time and resources to devising the solutions. The problem in that case is less of possibility and more of priority. If we made this our top priority, I am 99% certain we could have a successful colony on Mars in short order, but no one is going to make that our #1 priority. So, now we figure out what we can do with the limited resources we've allocated the project.
I'm okay with the sci-fi people being optimistic. Optimistic people make difficult things happen in the face of adversity. Realism takes care of itself.