Will the BTC price take longer to reach all time highs with time? 5 years ago 10k bought 3 BTC, now it buys .25. Does that mean that as price goes up, it will require more fiat to keep it pumping? When price is 200k, it will take a lot of money to influence price it seems. Even with mass adoption, it would require people to put it a ton of money to raise the price.
It helps to look at the market cap of Bitcoin in addition to just the current price. The total market cap of BTC is at 751 Billion $ at the moment. So it's a pretty simple calculation that the market cap needs to be at 7.51 Trillion $ for 1 BTC to cost 400k $. That calculation is not completely correct though because the supply, which means the total number of Bitcoins that is available on the market also keeps increasing because a new block is being mined every 9 to 10 minutes. So yes you are correct that the higher the price already is for 1 BTC the more new money is necessary to flow into the market and into BTC to make it do another x2 or x10 or whatever.