Republicans were is such a rush to provide tax cuts for the super-wealthy that they didn't think taking healthcare away from 24 million people would be a serious obstacle. It didn't help that, according to Republicans who met with him,  Trump wasn't prepared to negotiate because he simply hadn't taken the time to become familiar with the details of the bills or with how healthcare works; inviting Republican Representatives to go bowling at the White House wasn't enough to convince them to support a bill that even Trump suspected was a turkey. When he could have been doing a little homework so that he could negotiate intelligently, he was playing golf instead. Of course, the plan he bragged about during his campaign never existed at all and his campaign promises were meaningless.