Having a 20% stake in simple terms gives them 20% of the net...

Having a 20% stake in simple terms gives them 20% of the net profit back as a discount on each device they buy. Plus they get a share of the profits from every device their competitors buy too, further discounting their own unit pricing. So if our products really are better than our competitors, it will effectively bring the unit costs in below our competitors as well. So they get a better product and cheaper not to mention exclusivity on some product lines. Smart long-term thinking.