It's a large market, and more profitable than APAC and RoW per user (just look at the Meta investor presentations which show that it's US, followed by the EU then APAC and RoW[1]).
[1] https://s21.q4cdn.com/399680738/files/doc_financials/2024/q3...
[1] https://s21.q4cdn.com/399680738/files/doc_financials/2024/q3...
So if the EU goes to fines being "% of worldwide turnover"... do the math