Yes, because they are older (20 & 17) and need to see the big picture of how we got to be millionaires. It's not by livin' large but living below our means. Which translates to the lifestyle we're currently living, and how they get to go to college on our dime.
They need to know what a college education did for us, what science degrees helped us achieve and how that translates to them and all of our futures at this age of their lives. Um, and yes we still need to be frugal so they never have to worry about taking care of us, their parents in our old age. So with their knowing is the discussion of many, many things over many years. It's not just them knowing the $$.