I'm content with my few gray hairs, but I'll never dye my hair partially because it is too much work.  Most people start when they have a few gray hairs.  It isn't too bad.  As they gray more and more it becomes more and more obvious they have a dye job.  They have to have regular touch ups.  If they finally decide to go gray they look awful for 6 months to a couple of years depending on how fast/slow their hair grows and how long they want it.  That is way too much work.  I haven't even gotten a professional hair cut in more than a decade.  There is no way I'm going to a salon to get my hair dyed.