Rejection is part of growing up. While you may risk being rejected if you ask a person out, if you don't take a few risks, you gain nothing.
I've been turned down by more people than I care to count. I've also taken out more people than I ever would have imagined in my early dating years.
If you're "popular," you may get rejected one time out of ten. If you're not so popular (count me in), you may get rejected nine times out of ten...but that one acceptance is usually worth all the rejection before it.
As the saying goes, "you've got to kiss a lot of frogs..."