That might explain why in america more people in tech are diagnosed with ADHD, but would provide evidence against fewer people in europe being diagnosed with ADHD than in america (which is what the poster is asking about) since they have more access to healthcare, and it's not income dependent.

To answer the OP's question, I seem to recall that people with ADHD are more prone to be entrepreneurial (I believe a higher appetite for risk is the general explanation). Here is an article [0].

This would explain things if the people you know in tech happen to work for tech startups.

[0] https://www.forbes.com/sites/dalearcher/2014/05/14/adhd-the-...