Originally begun as a day off for government civil servants to decorate local graves for soldiers lost in suppression of the late rebellion, Memorial day was expanded to those service men and women lost for any purpose. That expansion was probably necessary to get the agreement of southern neo-confederates to the expanded holiday.
That number of US servicemen's deaths averages close to a thousand a year in peacetime, due to rigorous training, and the high rate of deaths normally seen by young men in the service members key demographics.
The bravest thing anyone can do is sign up. You then, with some degree of foreknowledge, accept the added risk of the service, and reduced control of the situations to which you will be subjected. After that, you are following through. Following through is not a trivial thing, but it is rare that our servicemen do not follow through. It is common for young men to not sign up.
All men die, and everyone dies alone. Not all die giving their last full measure of love and devotion to the last best hope of mankind.
Let us today remember the lives of those wonderful men and women who, by their service, have made us safer, and more free.