I just don't think it is accurate. Often pursuing something means giving up other things, which won't help you not to struggle in life. There is often no platea

I just don't think it is accurate. Often pursuing something means giving up other things, which won't help you not to struggle in life. There is often no plateau in menial or highly competitive professions. Trying to e.g. become a writer will leave you struggling for a long time. Unless some can provide for you in the meantime, which has little to do with your own focus. I just don't think focus as such is that relevant for whether you will struggle or not in life. A lazy programmer is still on average very likely going to struggle less than a dedicated service worker. There are plenty of, say, high school football players who have more grit than most of us but are doing worse in life than the kid who barely knew how to tie his own shoes.