Speaking publicly is huge fear for most people. Extemporaneously, and firing on all cylinders, in real time, is more than some professionals can handle. Itz a gift, for those who Can - so don't beat youself up.
Sometimes, saying nothing is the better part of valor anyway. It must be better than starting, and then failing.
https://i.mgflip.com/1zcck0.jpg
Shirley Temple apparently was given Grace under pressure - amongst her gifts. I put response down to perv.