The piano has been around for literally centuries. Mozart played the piano, and Beethoven, and Elton John. In fact, it has been the go-to instrument of tons of musicians for many different reasons. Many colleges even require a certain proficiency on the piano in order to get your music degree.
One of the reasons so many musicians gravitate toward the piano is its versatility. Articulating the piano is easier than any other instrument: just press a button. The piano can play the melody and harmony, even at the same time. The piano's range is larger than any other instrument, and it can fulfill percussive roles as well.
Another reason musicians love the piano is its value as a tool for composing music. Because the piano can fulfill so many different roles in music, and that it can fulfill these roles concurrently, the piano is a great instrument for exploring ideas in music to see how different ideas fit together. Vocalists can play chords and explore how melodies fit in with the chords, or a symphony composer can play the violin part with their right hand along with the cello part on their left hand to and see how they work with each other.