I assume you're referring to the gif of the German goal from the world cup. "Afraid" is a bit of a misinterpretation. When you're 5-10 feet from the other player and he's shooting on goal, especially if that other player is one of the best in the world, turning around is the only sane thing to do.

I remember Olivier Giroud breaking his foot by blocking a powerful kick from very close range.

So I think the answer is, there is a certain healthy respect for a ball kicked at close range by another professional soccer player.

EDIT: Also, looking at it again, looked like the player was trying to get in front of it, and just couldn't make it in time.

A soccer ball can reach 80mph (130km/h). Even with just 1 lb (~450g), that can make damages to your face - in fact, soccer is a common cause of serious sports eye injury.

And yeah, it's typical for players to turn around in a situation like that.

what an odd question. Ping pong is the only sport I can think of off the top of my head that I wouldn't be absolutely terrified of a professional athlete blasting a ball/puck/thing at me and even then just because i'm not terrified, that ball would still hurt pretty good

About 16 years ago I was playing in a ping pong tournament, where the forfeit for losing would be you had to allow the winner to take three shots at your bare stomach.

I remember many of the guys who lost had rather large purple welts on their stomachs, akin to a paintball wound.

This wasn’t professional level either. This was a bunch of Australian teenagers having fun in the evenings.