I read this article at Reason, a libertarian publication, and it explains perfectly why Trump's plan to "repeal and replace" Obamacare failed and should have failed.
In short, Trump is a dilettante when it comes to the substance of political policies. By all accounts, Trump has no knowledge of or interest in the details of his own healthcare plan. He seems far more interested in making a deal, any deal, than he does in learning what the policy actually entails and why people should support it.
Trump came into the office of the presidency with no understanding of or appreciation for the historical and legal minutia of the institution or the US government in general. I doubt he knows the difference between the Federalist Papers and Federal Express. If Trump has ANY hope of taking charge of the political agenda in DC, he better start educating himself on the details and substance of complex policies issues. Touting deals purely for their own sake simply isn't going to cut it.