Well, I’m not so sure. Steroids certainly cause health problems (and are illegal, along with cheating). And, Mr. Seau did not leave a suicide note, so who knows why he did what he did. Why is it simply assumed that repeated concussions was the cause. Steroid use could have been a contributing factor as well.
If players are willing to assume the risks of injecting themselves with steroids so they can be in the NFL, all these factors need to be studied.
If he had brain injuries, I would first look at his 20 years in the NFL as a linebacker. That is going to take a toll on a body.
A person who did steroids and limited himself to 5 years in the NFL, then retired, got off the steroids and promptly shriveled up to a normal size might have assorted squeaks and rattles for the rest of his life but is unlikely to be punch drunk.