Growth isn't an axis on the chart. The y-axis is expectations not growth. By the time of maturity Bitcoin could be a lot bigger than it was at the height of expectations, but have lower expectations.
This is a true statement in general, however simple arithmetic (ok, and some reasonable assumptions about use cases) implies that the price of Bitcoin would have to be at least 100x larger if it had, say, a billion users. So, if the price of Bitcoin
today was $5 million per BTC, then I would agree with you... the Bitcoin ecosystem could keep growing while the expectations (i.e., market price) would just keep going down (because expectations went unreasonably high, beyond the equilibrium value). However, at current prices, it's just impossible for Bitcoin to grow much more without also raising the market price.