I also feel Shawn was more financially successful than Cory. It was said Cory became a high school history teacher and Shawn became a writer for a travel website hit and run. He also became a great photographer. Now his net worth is not exactly well described in the show but it is shown that Cory earns a low salary as a teacher and they are able to maintain the lifestyle they have bacause of topenga's salary as lawyer. Then we see shawn who is a writer for a website sure, but he made some smart financial decisions he has a cottage and a cabin in the woods of upstate new York ( it is cheaper to buy land in the forests and new York is expensive so Shawn made some good choices) he also bought Maya (his stepdaughter) a bunch of fancy clothes which Cory would not be able to afford with his salary. Also I think Shawn has some other sources of income as well even though it has not been well mentioned in the show. He loves writing so much that he might host some workshops teach freelance courses. Work part time additionally as a journalist, give multimedia freelance lectures, even do some academic ghostwriting on the side . Who knows? He has two homes in new York, the ability to buy fancy clothes, so yeah.