1. In the US we got to see more other startups that were going really fast and that pushed us to go faster ourselves, Y-Combinator helped with this.
2. It was easier to find people that are experienced with modern sales and marketing practices in the US.
3. Customers in the US like to buy from a US company (and pay by check, these took 2 months and cost $70 to cash in the Netherlands).
4. On average companies in the US adopts newer technology sooner.
5. There was better advice and investment available in the US, Y-Combinator helped with this.
6. In the US there are much more success stories, this raised our ambitions.
I know many impressive startups and incubators in the Netherlands (shoutout to Adyen, 3ax Cycling, AppSignal, and Utrecht Inc.) and we have some awesome Dutch customers. The above examples and talking about the statistical average, there are awesome organizations and people everywhere.