Eh, usually Arts and Social Science have more girls than guys
what ... 
Not too hard to guess ...
As for rejection, you don't try, you wouldn't know.
Ai, to use back your analogy of going to war, simply put if someone
attacks Singapore and our NS men just say why bother since we are
all going to die and give up without a fight, then confirm
SIngapore will be lost lah. At least, if we all put our hearts,
mind and might together to defend our country, then whatever odds
against us, at least there is that CHANCE to protect and save our
families and our country right? 
But back to your case, I am reminded of the words of the great ice
hockey legend Wayne Gretzky who said that you will miss all the
shots that you did not take at goal ...
So why think so much? Just do it ...
Successful or not, at least you can pat yourself on the back and
say you tried ... 