The risk is too great? What risk exactly? The risk of becoming a trillion dollar company? Does every iPhone, Galaxy Android device or new laptop have a sticker on them that says "Product may have used child labor at some point in supply chain" in big bold letters? Will these companies triumphantly announce how their product now results in only 1 child death per year instead of 2 at some big keynote product launch event? No. Maybe they'll investigate after being called out and put it in some report that barely any consumers care to read.
If you sampled 100 smartphone users on the street about cobalt procurement practices, would they be surprised by what they hear? If you tracked those 100 people, how many would change their behavior(i.e. give up their smartphone) after hearing about it?