Trump didn't make any effort to push congress to improve it or start with something better to begin with. He instead attacked his own party threatening to "primary" anyone wouldn't vote for it as is. Trump owns a LOT of blame for this just on this issue.
And the truth is, Trump campaigned on forcing insurers to cover preexisting conditions which means it isn't insurance at all anymore. Go pass laws requiring coverage of your house after it burns down and it will go the same way... Trump also promised to cover the "25%" who couldn't afford the cost and said the "government was going to pay for it". So this Ryan bill gave Trump exactly what he asked for.
You can blame Ryan for giving Trump what he wanted but what Trump wanted is what's wrong.