C++ was invented at AT&T Bell Labs and introduced as C with Classes around 1986. This time frame coincidentally coincides with the approximate availability of PCs to the general public. If you read Bjarne Stroustrup's Biography of this time period—The Design and Evolution of C++—then you will learn that C with Classes was dubbed C++ and released right around 1990. The use of the ++ operator in the name is a play on the idea that C++ is an iteration of C.
The benefit of learning C++ is not that C++ is the best language or even the right language in all scenarios. In fact for many kinds of applications other languages may likely let you develop applications at a lower cost. No, the benefit of learning C++ is that C++ is an extraordinarily rigorous language. The rigors of learning the C++ language is like the rigors of any intensive training: one gets a more finely-tuned result. Here is another reason for learning C++. Because C++ was an early PC language a lot original object-oriented material was demonstrated and though of in the context of C++. In short, design patterns, folks, refactoring folks, analysis and design folks were all probably string C++ developers. Some of the most esoteric and powerful algorithms have been written about and demonstrated in C++ first—for example, read James Coplien’s Advanced C++ Programming Styles and Idioms book for some mind bending algorithms.
If you don’t necessarily have the time to take the 18 months or so it can take to learn the fundamentals of and write C++ then spend a little time becoming familiar with the basic grammar and syntax. Follow the study of the language through its grammar and syntax with the study of books on algorithms, idioms, object-oriented patterns and refactorings, and analysis and design concepts. You will find that studying this rigorous language—C++—and the literature that ensued will prepare you to master every other, less rigorous object-oriented language.
Of course, this is all opinion. However, because C++ is arguably the most rigorous language, its study prepares you thoroughly for less rigorous languages. Studying the material that ensued—the books in literature—contain information that applies to other less rigorous languages, like VB.NET and C#, and will help you use these other languages at a higher level.