As always in these discussions, I expect many people will start complaining about how expensive Mathematica is, and how Stephen Wolfram is very shortsighted with his pricing, and how open sourcing it would truly unlock all the potential of the system.
And I seriously doubt this point of view. Open sourcing is not a magic dust that automatically makes everything better. While it works in some cases, it doesn’t work in others - and not having a competitive open source mathematical system is a prove of that.
Hiring people to develop and evolve complex algorithms, on work on improving the UI and making it work on three different OSes, or curate and maintain the knowledge library, takes a lot of effort. I’m actually surprised they don’t price it higher!
Disclaimer: And yes, I live in a developed country, so $250/year for a personal license is not a substantial cost for me. I’m sure that somewhat biases my position.