A pyramid scheme is any scheme in which early adopters profit only if new money keeps coming in. I don't think you want to argue that Bitcoin's price can grow without influx of new money - bitcoin doesn't produce anything other than more bitcoins and heat.
I have already explained why a rational player would invest in a pyramid scheme (buy BTC at the auction), but I'll do it again:
1. Buy BTC below market at auction.
2. Sell on exchanges at market.
3. Profit.
Ok, I understood your point. But, who says that new monies won't come in and people won't profit anymore? BTC is still in development mode and has a lot to capture...
That's a different question altogether. There's always new money coming in, the question is "at what rate?" With Beanie Babies, for instance, it's sufficient for the actors to hodl their Beanies for the price to remain stable.
Not so with bitcoin.
Unlike the Beanies, which are no longer being
Enough fresh money needs to come into the system buy these and keep the price stable.
TL;DR: It's not impossible for the price to go up, but for it to go up substantially is unlikely. Just an opinion.