I really don't know why someone would give up the CLEA other than if they couldn't do the Fulbright at all (had a better option, didn't "pass" the health clearance, etc), or maybe if they didn't get into the language program they wanted and didn't plan any other alternatives. I only applied to one program, so if I hadn't gotten into it and all the other approved program's deadlines had passed, I would have had to decline the award. I was thinking more along the lines of a program not working out, or health reasons. Hope this helps! Good luck!