Why pay for Safety?

A little story about a friend. 
My friend was cutting wood with a new chain saw.  Everything was progressing well, lots of progress, sharp chain and plenty of wood to cut.  My friend had his safety gear on, safety glasses, ear plugs and steel toed shoes.  When he was finished cutting the log, as he had done hundreds of times before, he moved the saw, which unfortunately contacted his upper thigh.   Luckily, between the insulated coveralls, jeans and the key fob for his truck, there was no injury.  A near miss.   This is a great lesson learned, but not the only lesson to learn.
After talking with my friend, this is not the first time that this had happened.  He has other jeans that bear the jagged rip of the chain saw.  Why did he not learn the first time?  What was he thinking?
Well, turns out after the first time, he looked into kevlar chaps to protect his legs.  But, they were $100.  A little more than he wanted to pay. So, you guessed it, no chaps!!
Why is it that when it comes to accident or injury prevention, we are reluctant to pay money up front?  I know for sure that if he had actually cut his leg, he would have paid a lot more than $100, and wished he had bought the chaps.
It seems that for some people, they are willing to gamble that "it won't happen to me".   In case it does, I have workers comp or insurance to cover it.  But what about the non-tangible costs like pain, inconvienence, guilt, lost productivity, mobility etc.
In my book, prevention is a better route to take.  It is an easy concept to understand, yet our practice is not what we preach.