It's quite a complicated question to answer, and it depends how intersex is defined.

https://isna.org/faq/frequency/

> Total number of people whose bodies differ from standard male or female one in 100 births

> Total number of people receiving surgery to “normalize” genital appearance one or two in 1,000 births

I am going by Blackless‘s research. Even if that figure is wrong Klinefelter syndrome occurs at rate 1-2 per thousand which means that your estimate of one in ten thousand is way out.