First off, any insight into basic science always has far more implications than we can imagine at the time of discovery. Second, it’s taken us 100 years to see this. These people will be getting a nobel prize assuming it stands up to scrutiny (but the data looks great!). Third, we have a new tool to explore the universe with. It’s like discovering a whole new color exists. All the stuff that was that color before that we couldn’t see we can now probe. We can ‘see’ and find black holes that were otherwise impossible to find.
plus, now we can detect better how gravity comes into play, and eventually this might lead to anti gravity. So far every force in the universe has a polar opposite, so if we can find gravity waves, then we can figure out how to negate those.