White just revived and repackaged Miller's "Great Disappointment" trash she knew sold well and started making money. She's no different than the Rapture crowd who revived a doctrine that had been soundly rebutted by every major denomination in this country and rejected by all but a very few churches, repackaged it, and started making money.
That's how cults work, they scratch itching ears.
You feel better, now?
Your linked page there talks about the book written by Ellen G. White that heavily bashes the Catholic Church, called "The Great Controversy".
Just as an interesting (and ironic) aside, the SDA denomination is actually closer in one of their distinctive beliefs to the Catholic Church than they are to some mainstream Protestant denominations, and that is the fact they also do NOT believe in the "once saved, always saved" teaching of some Protestant groups. Like Catholics, SDA's also believe that people can lose their salvation (state of grace) through their own free-will choices.
Regarding "666", one other interesting aside someone has pointed out (sort of tongue-in-cheek) was that after hearing the teaching of Jesus on "eating His body" (the Eucharist) in John 6, many of his disciples at the time said that that teaching was just too hard to take, and this very sad verse follows that discourse:
After this, many of his disciples drew back and no longer went about with him. John 6:66