Kepler: "I have conclusively proven that the planets orbit the Sun in elliptical paths!

"But why do they orbit in ellipses?"

Kepler: "I have no idea!"

Newton: "I have explained Kepler's findings! There is an invisible force called "gravity" that attracts all masses in the universe to each other, at a magnitude proportional to mass and inversely proportional to the square of distance!"

"But what is this force, what causes it?"

Newton: "I have no idea!"

Einstein: "I have explained Newton at last! What we call gravity is actually the warping of space-time caused by massive objects!"

"But why do massive objects warp space-time?"

"I have no idea!"

There is always another why. For any mechanism explaining any phenomenon, there will always be another "why" you can ask. Science is ultimately about explaining our observations. And as any child knows, there is always another why.