(I base most of my Mormon comments on personal experience since I married one who left the LDS Church but frequently went back)
The deal with that is that some argue that Joe was just making offhand remarks about the future, the Constitution, and salvation and his buddies wove it into a prophecy when that really wan’t Smith’s intention.
Could also be that they knew that Joe was usually drunk (”The Jolly Prophet”) and frequently his mothings were actually whiskey talking.
That’s right-—the teetotalling LDS was founded by a heavy drinker.
At any rate, belief in the “White Horse Prophecy” is not universal among them and is not LDS dogma.
He and his father were known to be 'work-shy', unless it involved a scheme involving lost treasure.
I'm not so sure of that. When both Hatch and Beck publicly hold to the WH prophecy either openly or covertly, that should tell you something. In my own experience this "saving the Constitution when it is hanging by a thread" belief IS pretty universal among mormons, but like a lot of mormon beliefs non-mormons will hear a lot of "Oh, we don't believe THAT". There are quite a few "not for public consumption and I'll deny I ever said that" beliefs among the "saints".
In related belief, from the official LDS website on the post-millennium: