Here's why:

* Nucleus: The nucleus is the control center of the cell, housing the cell's genetic material (DNA) in the form of chromosomes. This DNA contains the instructions for building and maintaining the cell.

* Mitochondria: While mitochondria have their own DNA (mtDNA), it makes up a very small fraction compared to the DNA in the nucleus. mtDNA is involved in energy production within the cell.

So, while there is a small amount of DNA outside the nucleus, the vast majority of a cell's DNA is securely stored within the nucleus.