Apparently he’s made over £100m from his books. 
There are so many better books out there than that pile of repetitive mildly racist, stereotype-laden junk that he peddles off the back of being a bit famous. I feel sorry for all the decent non-celeb authors out there.
News article if anyone interested:
www.thetimes.co.uk/article/david-walliams-sitting-comfortably-in-100-million-book-club-gmp6bwm6b?shareToken=170904334320775f0850152088ce45a1