The
Book of Revelation is not the first mention of 666 in the
Bible.
Consider the following:
1 Kings 10:14
Now the weight of gold which came in to Solomon in one year was 666
talents of gold,
1 Timothy 6:10
For the love of money is a root of all sorts of evil, and
some by longing for it have wandered away from the faith and pierced
themselves with many griefs.
Of course everyone is free to draw their own conclusions.