Most software devs start at 2.5k in NL unless you're severely lowballing yourself. You're lucky to get 6k before becoming a principal SE or architect. 10k is a salary you're more likely to hit self-employed.
4x is possible, but in that short of a timeframe, you're more likely moving from a Dutch company to an international one and becoming employable across the entire globe. Which given US salaries would give the ability to 5-10x anyway.
Seriously 2.5k? Like the equivalent of 2500 US dollars (since Euros are at near 1:1 parity right now)? I looked it up and apparently the average salary in the Netherlands is 36.5k Euros. How is a principal SE making 20% of the average salary in the Netherlands?
I know some countries use decimals like commas are used in the US, so maybe that's actually 25000 and 60000, which would make more sense.
They meant per month. In NL we tend to discuss salaries per month. This excludes the mandatory "vacantion bonus", which is about a months salary. 2500 * 13 makes 32500 a year. So not far off from your figures.
That still seems incredibly low for a software dev salary, or indeed any salary (the minimum wage in Australia is not far off the equivalent of 15€ an hour, which is pretty close to 2500€ a month isn't it? Accepted the cost of living is higher here but I don't remember things being that cheap in that part of the world when I was there a few years back).
4x is possible, but in that short of a timeframe, you're more likely moving from a Dutch company to an international one and becoming employable across the entire globe. Which given US salaries would give the ability to 5-10x anyway.