The only thing that the Repubs had to do was work to FIX Obamacare. I've heard plenty of Dems (and even Obama himself) say that work was necessary to make it better.
Instead the Repubs and Trump wanted to go scorched earth on the thing just because it is tied to Obama (can't have the first black president with a lasting legacy). And now that they've helped destabilize it even further, they want to just drop it and blame the Democrats.
It's like if the Dems built a house but it needed some improvements. Then the Repubs came in, said they would build a better house instead of fixing what was already there, and proceeded to tear out half of the support structures, rip off the roof and pull the siding down. Then they realized they didn't know how to actually build a fucking house, so they just walked away from the gutted structure with a "good luck!" to the people who lived there.