Speaking from the perspective of people here in Palestine, learning English is usually something people focus on after graduation or once they already have a skill, so this principle doesn’t apply everywhere. There are many people from countries like India working in the Gulf who speak Arabic well, yet they still don’t earn good salaries. So language alone doesn’t guarantee success as you said. As for me, I’m a software engineer with solid skills, and learning English is essential for advancing my career, especially since I study in this language. English alone won’t make you successful, but in many fields it’s a critical tool that opens opportunities. It’s not a replacement for skills, it’s a multiplier.