Why do we not see as many chromosomal disorders in the population as we see genetic mutations?

Answer 1

Alteration of chromosomes often affects many genes and whole segments of the chromosome. This HUGE effect is most often lethal, so there are very few chromosomal disorders that are tolerable for survival.

Genetic mutation, on the other hand is often less lethal (though obviously in the right place it can still be lethal) as it usually affects only single genes and usually at one particular point, or small deletions that usually result in there still being a protein even if it isn't functioning quite right.

So basically, Chromosomal disorders are much more devastating, so rarely has survivors, while mutation is present in all of our DNA, and has a much higher survivor rate.