Genetics do not work that way.

The problem is that there is too little variation inside families and too much among families.

Let's say that there are exactly two alleles: successful and not successful. So, successful people pairs with successful people and have successful offspring, as you propose. But then, there should be little variability among successful unrelated families, and that is just not so.

Let's say that there are many different alleles that combine in lots of ways: then, there should be lots of variability inside families.