Actually, once one proves herself with some success it becomes easier to dare to focus on harder ideas. I see the signs of that at PG or Google's Larry Page and Sergey Brin. Once having tasted success, they feel anything is doable and possible. For the majority of start-up entrepreneurs, just succeeding the first time is the hard problem and requires ambition.

To what data are you referring? Surely there are also tons of smaller tech startups (or other small businesses) that were somewhat stable while small, but that failed directly due to their ambition.

Not only it isn't proportionally harder, but I think that Google feared your essay when you were indicating search as a possible startup.

First, Matt Cutts said "Paul's #1 suggestion is reinventing search. I happily welcome competition in search because it keeps us on our toes, but his #2 suggestion resonated with me more: reinventing email."

They just today released (for the first time, and they even call it huge news) a video about what they do on a search, I'm sure watchers must have thought that search is so advanced and hard seeing that video that they might give up ;-)

I wonder what pushed them to post this video. It's not even very informative, it talks about searches of N-grams and spell corrections, it seems more like something to show how advanced the changes they make are. It must be so hard to catch up with them ;-)

Maybe GOOG is afraid of a plethora of startups reinventing search. One may succeed.

"It's harder to work on an ambitious idea, but not proportionately harder."

Sure it may not be harder to work on an ambitious idea than to start an Italian restaurant (or the startup equivalent - something that is ubiquitous and stands a good chance of succeeding if executed correctly).

But although I acknowledge that the possibility of hitting it big from opening the "restaurant" is small compared to an ambitious idea, the chance of the restaurant succeeding and being an ongoing concern is magnitudes greater than the ambitious idea.

The simple fact is non ambitious ideas don't pay off for investors and that's why investors are biased to not encourage those types of ideas.

I think he is somewhat right. I do not think you can go directly after large markets. Most successful companies have gone for small markets that then disrupted large markets. I'm (100M exits are not that great for the record!).

Probably pretty true. I think the type of idea someone comes up with it greatly depends on the individuals personality, which also greatly impacts the success rate.

Where can that data be found if it is publicly available?