it's a zero-sum game regardless.

say bitcoin were a closed system. no more fiat influx, constant market cap. any gains any trader makes will be another traders' loss. someone selling coins they bought for $5 last summer for $27 picks $22 out of every pocket which bought coins at higher prices.

however -- and this is niko's point as well -- since the market cap is small compared to the potential market cap, there is an influx of fiat which might allow for huge amounts of deflation on the long term which means anyone holding btc now who is still holding btc then will get a really, really good return on that investment.

but even in this case, everyone will not become rich. if you mean everyone who has btc now, then sure, but that's a pitifully small number compared to the amount of people and fiat required to really blow the price that high, and the last ones to 'convert to bitcoin' will be the ones whose money we're taking.