If you can wrap your head around advanced C++ concepts and idioms, learning other languages will be a walk in the park. All the knowledge will be 100% transferable to anything you use in future. Also a lot of companies using java, c# etc will take c++ experience as relevant experience even though you aren't a java/c# expert, but the inverse is not true.
It's never a bad idea to learn something that has shaped essentially everything that has come along since.
First off, insulin is HARD TO MAKE. Its synthesized rDNA, this isn't the same as making pills out of powder from china and selling it at a 40% discount with plenty of margin still. This has to be grown and made in a lab with a very high precision.
Second off a bottle of insulin is like 25 bucks..... Boo freaking hoo. Most people cant wrap their head around how insane that is. You are buying f*ing DNA.. that someone made.. that's saving your life.. for 25 bucks.
What was the purpose of bell labs making unix or linus torvalds linux? Why is apache free? open source C compilers? python, java, mysql, go-lang, rust, angular the list goes on.
Open technology helps evolve the type of applications we can build. There doesn't have to be a "play". Facebook made something good that makes their lives easier and their product better. By open sourcing or sharing react whichever it is they allow other people to contribute which in part makes their product better but also increases the quality or reduces development time of the applications that anyone else using it builds.
I was in a strategical position with my last company and was an asset for a few reasons. When I gave my resignation my CEO said what do you want, name a number. I told him it's not about money, I need to move on to grow my knowledge and experience. I could have said 100k and would be happily making my 6 figure salary while in reality at the time I was worth half at best. (Friends at the company tell me the guy hired after me is making 110k, ouch).
BUT, since moving companies I've gotten my hands dirty, I've had opportunities to use tons of new technologies and I'm in sort of a lead developer role now. Im not making 100k but I'm damn sure much closer to being worth it then when it was just "offered" to me by my last CEO trying to prevent me from leaving.
My knowledge is now tenfold what it was before. I learn more and more every day and work on solving exciting problems. I know that whenever I switch companies next, or am up for a review I will be making a major salary jump because I have leverage now.
Strategic career moves that increase your value/skill/knowledge will always lead to more money in the end. Justifiable money.