Earl was making over 300K a year twenty years ago! He had 200K a year in endorsements alone. He had about five years with that kind of income and several more good years in the late 80's to mid 90's. And he did make a nice settlement (healthy six figures) on his million dollar score. Other players (Sigel and Varner) had similar success, maybe not quite as much as Earl though.
Mike Massey and his trick shot exhibitions trumped all the pros for earnings for many years. For the pros there have always been isolated opportunities to score big. Ten to twelve years ago the World Pool Championship paid 100K to the winner. Efren won a big event in Japan worth 163K, and we all know about the short lived IPT where several players (most notably Efren and Sigel) made high six figure earnings. Thorsten won 300K in one event! The problem was getting paid, although after it folded most of the players eventually (2-3 years down the road) got most of their money.
Of course the most successful pool players branched out into making cues (Bill Stroud, Danny Janes, Tim Scruggs, etc.), running events (Allen Hopkins), owning pool rooms (many) and owning their own line of billiard products (Mizerak and Varner). For myself personally, the only real money (100-200K per year) I've ever made in pool was owning two successful sports bar/poolrooms. It's not a fortune but it beat having to make balls for a living.