I don't think you're any more or less likely to get hurt and lose your earning potential officiating football than doing most other leisure activities.
Then again, if you have that in the back of your mind and you're going to be skittish about it, you just might.
If you are a reasonably healthy adult male, fairly ambulatory, your limbs work, you don't have periods where you zone out, the blood flows everywhere in your body that it's supposed to, there's no reason to be really worried about getting hurt out there.
If you have none of those things, you can still be an umpire.
(BTW, Joe Paterno is eleventymillion years old! And Charlie Weiss is about as mobile as your basic national monument. Unless you're a complete statue, don't worry about what happened to them happening to you.)