Why is Trump making a surprise recovery in the betting markets?

[ProfessorGAC]

6. Because The Books Aren't Predicting Outcomes

They're trying to draw money from both sides. A blow out attracts little money from the side sure to lose.
Every see the line on a game between Alabama and some div 2 school doing a money grab and letting their students get pounded?
They set that line at AL at -48 or -52. Absolutely nobody would bet the game on the other side otherwise. The book would take all money in on Alabama and lose it all. So, they set a line to attract money on both sides minimizing their risk of loss & maximizing their profit.
This is no different.
They go out with 538 odds of 88:11, and they won't even attract money at 8:1, because in a binary bet, few will put money on the severe underdog. So, they adjust their odds to attract suckers either betting with their heart, or living with 5:1 when that's not a good bet.