Mozilla is a 7 yrs old corp and started to do a commercial product a year ago or so. I don't know if KDE has ever done a commercial product, at least I am not aware of. We are talking about stories and companies which are a bit different than Jolla.
I think it's unfair to compare the values of some foundations (or Community Interest Companies) with those of a company. There's a huge difference. Foundations have alot more leeway, they can be alot more ideological. They don't have the same primary goals than companies: to create profits for their shareholders. They are not held responsible to some third parties that absolute demand for their investment for you to pay off.