This is just not true. There is a direct relationship between # of years of football played and not just likelihood of CTE, but also severity of CTE. Per a recent BU study: "Every additional year playing football was associated with 15% increased odds of a CTE diagnosis and, for those with CTE, 14% increased odds of severe CTE." Also, "Every 1,000 additional estimated blows to the head conferred 21% increased odds of a CTE diagnosis, and 13% increased odds of developing severe CTE." https://www.nih.gov/news-events/nih-research-matters/how-football-raises-risk-chronic-traumatic-encephalopathy