Was about to say youre crazy for putting a Spongebob voice actor over one from the Simpsons but after checking dudes IMDB, I see he's put in a lot of work.
How can I get into voice acting? A lot of people say that they love my voice.
Yeah, Tom Kenny does a bunch of stuff. Maybe he just wasn't on the list because The Simpsons has been running for 20+ years (and South Park too?) Even Family Guy started before Spongebob did I think, but Spongebob is just as well-known as those shows and should be making a sh*tload of money.
Anyway, just like stage and film acting, you gotta get into it through auditions, specifically at companies that need voiceovers. Typically, aspiring voice actors make demos of their voice (like 30-60 seconds) and send them to casting agencies and sh*t. There's a lot more to it. If you're ever in a book store try and pick up a book called by Yuri Lowenthal & Tara Platt (two other well-known VAs) its a cheap book and they explain the business very well and how to get into it.
Voice acting can be anything of course, not just cartoons. People get paid to voice for radio commercials, narrating documentaries on tv, voice acting for video games, etc.