I hope Taron's post playing career health is good.
That said, it's one thing to get a concussion playing rec soccer or middle school football...of course stop playing, maybe forever at some point.
Whereas Johnson is an adult who is being compensated more than $6M per year for his avocation.
Generally speaking, the market rewards risk taking with higher returns. That's what's going on here.
Aside from concussions, NFL players are taking all sorts of physical punishment that will cause them significant problems later in life. It's their choice. Some guys walk away (ex: Andrew Luck) because of it.
Regardless, I hope they are making good decisions for each player's long-term health.