Talent may be BS, but difference in memory, learning, and concentration are not. So while everyone can improve some people have easier time and higher ceiling.
There are probably many genetic/out-of-your-control-environmental effects which strongly influence your chances of success, but learning, concentration, and memory can also be practiced and improved upon like any other skill.
... yet none of it matters without discipline.
Not everyone is born with good discipline. Otherwise everyone would be super successful. We all are slaves to our genes and environment, some are born successful some are not.
Almost everyone can force themselves to improve their discipline though, sometimes with the help of medication where necessary.