I do believe he was being facetious, salvation.
The Life Application Study Bible lists Mark’s occupation as missionary-in-training, Gospel writer, traveling companion.
It also states he was a young man (Mark’s own words about himself), so it is possible he had not yet chosen or begun a profession out in the world before he met the other disciples and decided to join them.
But the majority of the disciples were indeed fishermen.
Btw, this is a wonderful bible. The profiles on biblical people, the chapter notes, and the index at the back are invaluable. Highly recommended!
I’ve always thought that Mark was the man that ran off naked as Christ was arrested. Don’t remember where I read that explanation.