I think that we measure in dollars or euros because we need some metric for comparison.

For example, if you live on the beach where the water is shallow, you'll experience high tide and low tide. The beach itself gives you a measure of how high or low the water is.

However, if you're in the middle of the ocean with no beach in sight, then you don't experience a tide, even though there is one.

Similarly, with Bitcoin, when we measure everything by Bitcoin, we don't really know if something is cheap or expensive without some dollar or euro comparison. If something is 50 sats today, we can expect it to remain at 50 sats for some time even if the value of Bitcoin has gone up or down. It's only when we compare to dollars or euros that we know if we should pay more or less sats.

We're not at the point where we become indifferent to where we will pay the 50 sats regardless of the market fluctuations.