Not quite, he was comedian who was on stuff like Mr. Show before he became a VA, so he was doing well for himself before the sponge gig.
Now there are many people who do voice acting as a side thing and have a lot of on screen expereince as well: Phil Lamarr, Clancy Brown and Ron Perlman, for example.
Not mention a lot of VAs like Grey Delisle have careers as singers as well as VAs.