Why is there a star at the end of my 50 dollar bill is it worth more?

A star after a US bill's serial number means it was printed to replace a bill that was damaged during the printing process and had to be destroyed. In general "star notes" are worth a bit more than ordinary notes with the same series date and letter. A 1969 $50 isn't rare so you might get an extra 5% or so for it, which might take its retail value all the way to $65.