I admit it's not exactly a pyramid scheme, but it does have many features in common -- in particular, the fact that the folks who get in on the ground floor can potentially earn lots of money by persuading as many other folks as possible to join in and then cashing out before the bubble bursts.

In a pyramid scheme, the people at the top of the pyramid want to stay in the game for as long as they can, not cash out as soon as the opportunity arises. What you've described sounds closer to "pump'n'dump".

And people who first got into computers benefited greatly by convincing others that to get into computers as well.

I mean, the more widespread the use of bitcoins the more negligible the initial advantage of early adopters will become.