Newtonian physics is not wrong, it just doesn't work well outside of its model. Similarly, neither are relativity and QM wrong, despite breaking down outwith their models in extreme circumstances, such as within singularities.
Expanding on the theories (as relativity did to Newtonian physics), doesn't invalidate the previous one. Fundamentally, the theories that physics have been working on for the past 300 years have never, ever, been wrong (they're all basically underpinned by Noether's theorem). That is why we can say with certainty that some things that we cannot observe directly, but can see through their actions on observable bodies combined with math describing them, are simply 'fact'.
Trying to observe them (like we did with gravitational waves) does two things. First, obviously, is the attempt to prove the theory with a repeatable and observable method (as is the staple of the scientific method). The second is to try and disprove it exists... because if we managed to invalidate the standard model, physics would get a whole lot more interesting!
Sadly though, the reality is it is absolutely bang on and we're just checking off entries in a list.
