History is littered with counterexamples. If you look at people or companies that have been refered to as "ahead of their time", it is frequently in the context of why they ultimately failed.
Tablet PCs are a case in point -- Microsoft or HP had not abandoned the tablet market. They were iterating and releasing tablets even after the iPad was released. They just didn't make the leap that Apple did to create a tablet that appealed to the masses.
Also, regarding the "riskier to be too late" comment: The book "Copycats" by Oded Shenkar makes the case that it's frequently the imitators that win the market rather than the innovators. This blog post reviews it and cites some interesting statistics from it: http://www.ribbonfarm.com/2010/08/03/down-with-innovation-up...
"They were iterating and releasing tablets even after the iPad was released. They just didn't make the leap that Apple did to create a tablet that appealed to the masses."
I think this is a succinct refutation of the Tablet PC being a counterexample to something "ahead of their time". The lack of success of the Tablet PC wasn't because it was "too early for the technology", but it's because Microsoft and HP were developing the wrong device for the wrong market.
That said, I do tend to agree with your premise that you certainly can be "ahead of your time", and that being first to market does not always correlate with being the best to the market.
I guess I see "being early" and "building the right product" as orthogonal. Microsoft / HP built the wrong product for the wrong market, but that's not necessarily because they were too early!
Tablet PCs are a case in point -- Microsoft or HP had not abandoned the tablet market. They were iterating and releasing tablets even after the iPad was released. They just didn't make the leap that Apple did to create a tablet that appealed to the masses.
Also, regarding the "riskier to be too late" comment: The book "Copycats" by Oded Shenkar makes the case that it's frequently the imitators that win the market rather than the innovators. This blog post reviews it and cites some interesting statistics from it: http://www.ribbonfarm.com/2010/08/03/down-with-innovation-up...