Nobody knows for sure, yet, but ....
The "pyramid scheme" complaint is heard a lot out there about Bitcoin (and the other "alt coins"). Personally, I don't think it's the same thing.
With your standard pyramid scheme, you typically have a business of some sort that claims to offer some great, profitable product or service. The people who get in on the bottom make big profits recruiting more people to sell (because some sort of commission is usually paid for signing up more people, and it turns out that's really where the profit is).
Eventually, you have so many people in the program, the last ones in can't find anyone else to sign up, even though they've all paid for a supply of products to sell (or whatever up-front costs had to be paid to be able to perform whatever service the company claimed to perform). So the company owner made all his/her money selling all those overpriced products or "getting started" packages for the service, and the first group in made a big profit signing people up. Everyone else loses.
If you try to compare that to Bitcoin? For starters, there is no one "company" involved. Sure, there's someone who wrote the code for it in the beginning, and I don't doubt at all that guy profited by mining and hanging onto a bunch of Bitcoin before everyone else got into it and raised the difficulty levels. But really, so what? It's not like anyone else was going to pay him for all of his work coding it. Doesn't he deserve to be successful for designing a whole new type of currency that winds up in world-wide use? Besides -- it was FAR from a sure thing it would even go anywhere. He took a big chance putting all the time and effort into coding it that it might not have ever caught on, and would have just been a big waste of effort.
But also differing from a pyramid scheme, the more people who take part in it, the more legitimate the product (the Bitcoin) becomes.
The "mining" aspect is really only a portion of it. Bitcoin is designed so eventually, a hard limit will be reached on the number of coins in circulation and mining will quit making any new coins after that. (As the limit is approached, the mining, again by design, will become more and more difficult -- meaning less profitable in the sense of new coins appearing in the miner's electronic wallet.)
As this gets closer to happening, more and more users of Bitcoin will start focusing on treating it like cash money instead of a money-making scheme where you invest in computer power to make Bitcoin out of thin air.
Since each transaction still requires multiple mathematical verifications of its validity before it's considered "processed" - the systems doing this by "mining" will still be a critical part of keeping the whole thing functioning. By the time there's little or no more Bitcoin to be generated though, the currency will hopefully be established enough so these people can turn it into a business model of getting paid a small cut of each transaction. (Not unlike what every other payment processor on the planet does now, such as credit card processors or bank wire transfer fees....)
And this makes me wonder what's all about and why I think that's a pyramid game. The winner are the early joiner and maker of ASICs. Nothing get produced except a big bubble. Plus there is no chance for growth. I read somewhere the maximum number of coins/value is limited. So there will be a time where you have to put more in to get less out. Like oil digging these days.
But hey, have fun with mining.
