I found your post due to the mention of 401K and investing which is my interest. Ironically its not yours :). I am not a fan of 401K's because of their restricted architecture and future tax liability however for W2 earners' free money from your company is hard to beat. Therefore we must teach ourselves to make the best of this asset and not as you say simply throw it to some mutual fund manager we have never met.

There are many successful entrepreneurs as you say who point to diversification as a bad thing. However the simple downside of investing everything in yourself is who will look after when you can no longer do so? I believe in multiple unrelated buckets of income because there is still the unexpected in life.