As of January 2010 it had been featured in 2,400 newspapers worldwide and there are 18 books with combined sales of nearly 45 million... Reruns of the strip still appear in over 50 countries.

He's married but has no children and seems, from what you can read, to live a relatively modest life.

I'm assuming that adds up to being secure and I suspect if it were to go one way or another from secure it would go towards being very well off indeed.

If he lives as modestly as I suspect, he may be able to easily live off the growth of investments on one or two million dollars. :)