We don't, as evidenced by the fact American football and other contact sports both aren't banned and are extremely popular. We can still criticize the league f

We don't, as evidenced by the fact American football and other contact sports both aren't banned and are extremely popular. We can still criticize the league for downplaying/covering up the risks of brain damage. After all, to make a proper cost/benefit analysis you'd need to know all the (known) costs.