Not necessarily. It will take the same amount of fresh capital to raise the price from $ 50k to $ 60k as from $ 100k to $ 105k. Therefore, we may not have such large price fluctuations in the future and the value of Bitcoin will become less volatile. That doesn't mean we'll need more and more fiat for the new ATHs but the potential return on investment will certainly decrease.
Who knows, maybe one day we'll equate cryptocurrency returns with some other investment assets, like stocks or gold?