The coin is issued by a central entity who has kept 50% of it. This makes people suspicious. Bitcoin has no central issuing entity, thus no one person to 'get rich quick' in some scam type operation.
Yeah, the early adopters got rich. I think that's fair because they invested in something that was really uncertain at that point. You could even argue that if you buy bitcoins now you're still an early adopter.
Bitcoin itself is less of a pyramid scheme than gold. This is because even when the price stops to rise (or even when it collapses) you can use it to easily transfer value across the world.
