Cleantech/greentech was originally defined as "non-energy", because energy had a long history of being investable. Energy efficiency and generation is a great sector for investment (I am so excited about Bloom Energy and Lightsail and FLiBe). I'm not at all excited about most of the ex-energy investments, and it appears most of those have failed to the extent that people consider energy part of cleantech now.
They were crap as investments, and most of the non-energy investments had bad science too, as well as being badly managed.
I'm totally pro-environment and pro-efficiency.
In the specific case of KPCB, they did a pretty horrible job with a lot of their portfolio. Missing Tesla and taking Fiskar was a great example. They did get Bloom. But I don't think they were approaching the sector with the kind of scientific and business rigor they used in the past for their other investments, and they were punished for it.
Considering that climate change already kills 150,000 people per year [1], and that this rate will continue to (dramatically) increase, I think it's pretty rude for you to belittle the few good people who choose to fund cleantech (putting their fellow man above short-term economic "rationality").
[1] http://www.who.int/heli/risks/climate/climatechange/en/