Ask HN: I've got 3 months of long weekends. What should I build? 15 years ago
I vote for 2.
If you are able to create an original theme that offers something new to designers and developers (who are the main customers of premium themes) you can make thousands of dollars in only a couple months. Study the themes with several sales to see what they have in common and incorporate those things into your own theme.
It's also a great opportunity to find customers looking for support and outsourcing.