I think people reading random tweets from random people gives them a roller coaster of emotions because they're getting random bits of scattered stories told second hand, sometimes in passing or being overheard.
Looking at just these factors
- The country's largest lobby, AARP, is very much opposed to this law, and is threatening to shame every single person who votes for it
- The Heritage Foundation, the Conservatives "go to" think tank, is opposed to the bill and is threatening to score votes for the bill against people (and they take these scores seriously)
- The Koch brothers, the best known and one of the largest GOP donors is against it and is actively promising PAC support to anyone who votes against this
- Paul Ryan has stopped saying it's going to pass and has instead moved onto "it's going to be voted on" which means he's done
- The White House has completely given up. Trump is bored (and made that well known) and is already blaming people for the bill failing
- The yes/nos have only changed +/- a couple of votes over the last 24 hours, with it trending towards nos more. This isn't a good sign for a healthy bill that's about to pass
If this was any other bill, all those factors would mean it never even saw a vote, let alone passed.