Up thread a mention was made about all the folk killed in F1 in the late sixties and early seventies. Actually it was in almost every level of professional racing at the time.
But autoracing is also a great example of technology removing most of the risk while not effecting the sport itself. But it took three things, first a public outcry that simply said "This must Stop!", a willingness for the sponsors to fund the additional costs involved in improving safety and they were significant costs and governing bodies that said "Unless you follow these construction standards you don't get on the track!"
I believe technology can help but today I simply don't see either of the other two factors in professional football or any of the gladiatorial games.