Europe is a big place and covers at least 6 different kinds of lifestyle and 3 kinds of weather. That's a few shades of grass to try before you give up entirely?
And, like the article says, you have options. For anybody still on the fence, I can't recommend leaving the UK enough.
2016 year of the chav.
The ethnocentrism is prevalent in US startup culture as well, it is overwhelmingly white and Asian with Hispanics and African-Americans being left out. Underprivileged minorities face steep challenges in the tech industry, almost regardless of geographical location.
[1]https://www.recode.net/2017/6/1/15725826/steve-case-revoluti...
2. The entire European pie is roughly 25% of the US.
3. That's racism and it's a problem in the EU too, albeit less recognized. The ethnocentrism is an additional, different one (and it only amplifies racism). It's the way European national identities are defined mostly along ethnic and linguistic lines. American culture and identity is 100x more universalist than the European ones. This means not only will people have a harder time seeing you as one of them, you'll also have a harder time seeing yourself as one.
[0] https://medium.com/yankeesabralimey/european-israeli-venture...
France and Italy as two very large countries stand out, the former because it's very closed up culturally, the second because it's not in a good shape politically.
I won't deny that the US has a more open culture (having experienced both myself as a German citizen who has worked in the US) but the gap is not so large any more that the generalisation is valid without qualifications.
Sure, there are many nice cosmopolitan cities in Europe. If you want to get a few year-long stint doing whatever - not a problem.
What happens once you get children? Are you going to send them to a local school and have them grow up speaking a language you hardly know? If you're Jewish aren't you going to worry about your children getting hurt? If you're an Arab aren't you going to worry about your children being othered? If you're not a Christian, can you fully practice your religion? (i.e. some European countries ban kosher slaughter, there are plans to ban circumcision, burqa bans, Poland just made talking about some parts of the Holocaust illegal). How certain are you an EU citizenship will mean a thing in 10, 20 years? How strong are your property rights? For how long has your European country of choice been a safe, welcoming place?
For some people these aren't big problems, that's okay. For those that do worry about these, they aren't being picky or unreasonable. US is simply a better, safer deal.