1) I dont know any one man bands who managed to clone a business with no real insight and backing. Virgin was owned by Branson who had both a clue and money.
Whose to say that the OP doesn't have huge backing?
Whose to say that the OP doesn't have a intimate knowledge on how to launch a business?
You say that the backers of Google or Facebook were not crazy. Yet you state that creating or investing in a copycat product/service/shop is folly (referring in your earlier post: "if they went ahead Id happily part fool from their money").
At the time when Facebook was up and coming, there were other social networking sites which had bigger numbers. The idea of social networking had not taken off at this point.
Similarly when Google entered the market in earnest, there were already established search engines. The big ones were Alta Vista and MiSN search, owned by Microsoft (the software giant). Are you seriously telling me that you would've invested in Google, when their intention was to battle with Microsoft and Yahoo?
You also then go onto ridicule the idea of a 1-man band (ie. a small setup), yet Google was started by 2 University students. Facebook was started by a few University students.
At the end of the day, all businesses are inherently risky. Some carry more risk than others. And others have potentially more rewards. You have to measure risk to reward ratios and have to see if the investment is worth your while.
To brand someone as a "fool" is wrong, as that "fool" may end up creating/investing a copycat service which may out perform the original.
Also, some of the best and most original ideas never take off, while some poor ideas which are badly implemented, may take off.
Luck plays a huge part and in most cases it is impossible to tell which idea will become huge and which idea will amount to nothing.
For this reason most investors will invest in 10s, 100s or 1000s of companies, hoping that 1-10% of those companies become huge. Most companies will amount to nothing. Most investments will fail, which is why I find it strange that you state that you are able to tell which companies/startups will prosper and which won't ("I've been around a while and can spot ideas that look decent and what looks silly"). If you can truly judge this correctly, then you are probably the only person on this planet who can and most likely, you are already a billionaire.
I would also ask (genuine question) which startups you think, in August 2012, will become big over the next 5 years.