If you believe the multibillion-dollar firms behind “prediction markets” and the individuals who are handsomely paid to promote them, two things are absolutely clear: These exchanges are not gambling, and they certainly don’t prey upon young or vulnerable people. But many lawmakers, as you might suspect, don’t seem convinced. Undeterred, the industry has been furiously adding to its roster of lobbyists and advocates over the past year, hoping to build on the Trump administration’s support,