No they aren't. Even if you narrow it down just to white Americans, British ancestry is almost even with German and does not hold a majority once you include Irish, Italian, etc. [1]
I don't blame you for thinking they are tough, as Anglo culture and language has been unusually dominant, probably because the original 13 colonies were very Anglo and the whites that trickled in later largely assimilated. "Albion's seed" is an interesting book on this topic.
[1]: https://www.census.gov/library/stories/2023/10/2020-census-d...
Edit: British doesn't usually denote an ethnic group so I took it to mean Anglo, but if you take it to mean Anglo+Celtic then it would indeed make a majority of whites in the US due to the very large Irish population.
That's fair but I'll also point out that pan-Germanic (including Nordic) ancestry is actually the majority in many Midwest and West coast states, while the northeast is obviously very Anglo. So you can get a very different impression depending where you spend your time.
Wildly inaccurate
People are multifaceted. We’re complex and sometimes irrational. I can also believe that you can share certain views yet still not be fully embraced or respected for them.
As a crude example, a Caucasian man who was born and raised in Japan thought of himself to be Japanese ideologically. Yet to the Japanese he was always an outsider - as a result, he has never felt truly at home anywhere.