Earlier quoted context omitted.
What if you have an IQ of say 90 and want to be really good at theoretical physics? I don't see caring a lot and working continously as enough to overcome IQ here.
Care a lot and work hard. IQ in later life is only correlated with IQ in childhood., it's not a fixed trait. https://www.psychologytoday.com/us/blog/beautiful-minds/2011...
I had the opposite experience. I've had various IQ tests at age 5, then 9, then 16, then again in my mid-late 30s. 7 tests in all. They have various scores and scales, but in every case, I was within spitting distance of the same spot on the various scales of each test. In some cases, I didn't know I was going to be tested - no prep. In other cases, I'd planned the tests, so ... I can't say I "studied" as such, but I got good sleep, was relatively(!) calm, not anxious, etc.
I don't doubt that over time intelligence capacity changes some, based on a variety of factors. My own experience is that it doesn't change much - both with myself and people I know. It may be that I already tend to know people of above average intelligence, and there's less room for them to grow in the first place?