The point is that most companies don't get to the point that the difference between C++ and Python matters. Worrying more about the business and less about the technology will be more likely to see you succeed than worrying more about the technology and less about the business.
I don't believe all companies can survive with a python or ruby solution. I do think that, as technologists, we worry too much about the "optimal" solution to technical problems when, in most cases, businesses are made or lost in people problems. People problems are really hard because there are few "right" answers. Instead, it is an optimization game, and optimization games require agility.
If you are that amazing at C or C++ that you can iterate amazingly quickly with them, then use them! That will give you a leg up later. I've been developing software for 15 years and have use everything from C and C++ to Java to Python to Objective C; and I've seen a massive difference in my ability to iterate with each of them.
Optimize for what works best for you, but don't be surprised if you choose C++ and a competitor who doesn't care about the "perfect" solution runs circles around you in the market because they chose something different (even if they re-write in C++ in 10 years, after they've stolen all of your customers).