Yes, you're seeing the selection effect at work.

I've started two startups now. While I'm very nearly the most even-keeled person I know from an emotional standpoint (I've been described as "a robot", "mellow", "a cold fish", and worse), a couple of years of running a startup is like being bipolar. Perhaps for folks who are already bipolar without outside influence, it's even worse, I dunno.

Here's how I think it goes for most startups:

Stage 1

Great idea(s). I have a blinding flash of insight--first time my insight was "the Internet is too damned slow!" (in 1999, this was a pretty good insight). This time, with Virtualmin, it came as the gradual dawning of a Many Faceted Great Truth rather than a flash. These feelings are akin to messianic visions of the past. If they weren't we wouldn't be willing to quit our real jobs and spend three to seven years tilting at windmills to make them happen. This is exciting and very uplifting. I bet Jesus felt pretty good, too, when he woke up with the flash of insight that he was the most important human on the planet (and a god to boot!).

Stage 2 (where most folks start showing up to events)

Talking about the idea with friends and peers. Taking this leap of committing to the idea enough to share it with others and defend it feels like an accomplishment, which is emotionally rewarding. You get some validation, and you maybe spot a few problems and you work through them, which also feels good.

Still feeling great at this point. But you haven't actually done anything.

Stage 3

Now you've got to build something. A demo, if you just want to get to that next stage of big validation that is raising money. This one is harder. If you don't actually have the level of skill you thought you did (and we all hit this sometimes, no matter how great we might be at some areas) you run into roadblocks to completing this stage. This is where folks begin to drop out of the event scene and start to think maybe this whole startup idea wasn't so great after all. I've occasionally run into roadblocks that took me weeks or months to resolve, either by learning enough to scale the wall or by hiring or befriending someone who happened to have just the right knowledge (this is harder than it seems). And these are the worst parts of the ride.

Stage 4 (wherein validation reaches new highs)

Money. Some folks get addicted to raising money, and never actually get around to building their product (these are the same people who never actually succeed, by the way). When you raise money, not only is someone saying, "Yeah, that's a pretty cool idea", they are saying, "I'm putting my money where my mouth is, and I'm placing a huge bet on you being a big success."

However, before you get to that validation you will get numerous "no" responses, and that's usually a big downer: people are saying your baby is ugly, and kinda stupid. And you can't punch them in the mouth for saying so.

And at this point, you cycle between Stage 3 and Stage 4 until you fail or build a real company that makes money. This cycle is somewhat arbitrary as to how you'll be feeling at any given time...but the first two stages are action packed excitement all the way. Nothing can go wrong until you actually start doing something. Of course, nothing can really go right either...but you'll feel like everything is going right and clicking into place, because humans are funny that way.