I prefer to be paid based on how valuable my work is to the employer, not the cost of living wherever I happen to be or even my personal financial needs.
Sure, so do I, but when I tell my manager I'm worth X amount, he'll say that's just not where local salaries are at for my job category and responsibility.
Implying that other developers in my area are available for less than I ask.
I mean, if a person is able to extract 700€ per day, kudos to them but that's still above the 90th percentile of senior developers in Europe.
What do other companies say? "Nah you're not" is a pretty standard response to "I'm worth more than this" but consider the source. For some reason many companies would far rather let a good employee leave than raise their pay to market rate.
I had a buddy do exactly that. His manager told him he was already paid above market. Inside a month he showed her that she was wrong and we had a gaping hole to fill in the team.