If you want to know why Trumpcare failed so disastrously, here's a big part of the answer:
The process toward passing Obamacare began on March 5, 2009, when President Obama convened a "health summit" with various players in the health care industry. It finished 383 days later, on March 23, 2010, when he signed it into law.
Trumpcare began life on February 16, 2017, when Paul Ryan released an outline of what a Republican bill would look like. It was abandoned 36 days later, on March 24, 2017.
And this doesn't even count the fact that Democrats had been seriously debating and designing health care policy for decades before Obamacare was born. Republicans had never gone much beyond the debating point stage. But policy matters: detailed, messy, real-life policy that makes compromises in order to produce something that works and has the support of all the stakeholders. The problem is that Trump isn't used to that kind of thing. Ezra Klein points out today that, in fact, Trump isn't a very good dealmaker. That's true, and it's something I've written about frequently. But he also says this:
In Trump’s past jobs, he could simply move on from failed deals and find new partners, and new markets, and new sectors. But that’s not how the presidency works, and it’s not clear he realizes that.
"Take it or leave it" works only if you really are willing to leave it. Trump often is, because he can always turn around and do a different deal with someone else. But there's only one Congress. If Trump gets bored after a whole month of negotiations and gives up, there's no other Congress he can turn to. That's why Trumpcare is dead.