(I do get the joke here but...)

Einstein didn't discover GR in any meaningful way. It was always implicit from Special Relativity, it just wasn't at all interesting. Also, the legend is that it took him 7 years to work it out, but the reality is that it took him six years of milling about, and then a few discussions with David Hilbert who showed him what to do.

Once 'discovered', the entire theory solves one problem -- the precession of mercury. You can also argue that it helps us with certain aspects of GPS timing etc, but not really, because engineers have to calibrate the system anyway, and they're not using GR to do it.

The flights of fancy (wormholes, blackholes etc) are... well, flights of fancy, because they exist within a theory that we know doesn't describe the universe to the required precision. And the connections with the 'BigBang' are somewhat meaningless, because that theory requires the introduction of 'Inflatons' to hold together.