- Did you learn to walk on your first attempt? Probably not
- Did you learn to ride a bike on your first attempt? Probably not
- Did you learn to talk on your first attempt? Probably not
Ok, how about closer to home - you're a developer, right?
- First program worked perfectly? You've learnt no technique since?
Startups are no different - it takes many attempts - if you're lucky, the startup does work out "first time". But there's a fair chance the product or service that succeeds is in no way related or even close to the one that was started with. Invisibly to the public they're scrapping, reinventing, shouting, panicking, getting within hours of the money running out, working til 5am, until the product emerges, apparently perfect first time. For them to be an ...
... "overnight success". You'll find they've been marketing, blogging, interviewing, sending press releases and working like maniacs for years, until the buzz finally caught them.
I suggest you add Founders at work to your reading list - you'll see some of the stories of the early days of some of the well known companies. It's not the easy big hitting you seem to believe.
Paypal - success first time? Nope - they were a cashless payments app for Palm, which was going nowhere. I think the idea was something like beaming payments over IR to another Palm.
37signals? Basecamp was an internal app used in their main business of web design. Which one day they decided to try selling. They don't do web design any more as Basecamp turned out to be a little bit successful.
Flickr? It started out as an MMO. They added in chat and real time photo sharing and a few other things and it turned out people really liked the photo sharing. Then they realised people wanted to share photos and leave them available. iirc the chat got progressively more hidden until they could kill it. The game never saw the light of day.
The two founders of Flickr finally got around to something like the game they were thinking of though: http://www.glitch.com/ Just took them a decade and a completely different company and product to get there :)
The common thread through them though is they were happy to kill the main business when they found something better that worked. If they hadn't, chances are many of them would have been long gone and you'd never have heard of them.
The first bright idea may be great, but even then it'll need a lot of adjusting and rethinking to get customers to want it, and to be able to sell at a profitable price, and cater for the 55 things you never thought of. It may equally turn out to be a brilliant idea that no one wants to buy. In both scenarios you need to come up with something different - ideally using the lessons you just learnt.
The key is recognising when you need to transition, or when plan A isn't working, and not to give up, but to try plans B and C.
Now, if you like the idea you're being offered, and you think you can believe in it - go for it. All your previous startup experience gives you is additional valuable experience of a scenario that didn't work, and a couple of skills that aren't your forte. Perhaps it was also simply not the right time for the offering. But it's not a negative to stop you doing it again.