Google's John Mueller responded to a Reddit thread where the webmaster didn't understand why a competitor of his was outranking his site when the competitor had a page speed score of F.
John Mueller responded saying "The nice part about using so many factors for crawling, indexing, and ranking is that you don't have to do everything exactly the same way as all of the other sites are doing."
Yes, just because a site isn't doing well with one specific area - it doesn't mean that site cannot rank well in Google. In this case, speed is one of hundreds of factors Google uses and I believe speed is not even a really huge factor compared to other factors in the mix. You still want to make sure your site loads fast because the user can simply click back and go to the next search result listing in Google.
But you don't have to be discouraged when you can't do well with a specific metric. Just focus on what you are good at, excel there and you should see success. The algorithm does allow for SEOs to be unique in their own way.
Forum discussion at Reddit.