A recessive gene doesn't mean it doesn't exist, just that it doesn't get presented. Someone can carry the gene without expressing it.

For example, if we have a parent with brown eyes, and let's say they have 2 copies of that dominant gene, we will call that BB, and a parent with blue eyes, they kust have 2 copies of that recessive gene we will call by. The child will have one of each copy, to they will have brown eyes, but will have the genes Bb. If they have a child with another person with Bb, then they each pass one copy on at random. We can get B from both, resulting in BB brown eyes, or B from 1 and b from the other, resulting in Bb brown eyes, or they could get blue eyes and have bb.

Recessive genes just mean it's less likely to be expressed, but it's just as likely to be passed on.

Dwarfism is a dominant gene, but it's not taking over the genepool. Although is mostly due to the fact that having two copies of the gene is fatal.