Thanks, Patrick. I meant to exclude consulting. I'm thinking of something that happens in your sleep, like a "safe" investment would. Web apps/niche software are where I would lean as well but that's why I'm asking. I'm hoping the collective experience of HN can expose other options.

create a niche software product with recurring revenue in a day or 2? Sign me up, i'll take 10!

I meant that if you were willing to count a few days a month as "not really working", then you can trivially bill $2k quickly. Otherwise, niche software is an option.

I think the parent meant you could make that much money as a consultant in a couple of days, not create a niche software product with recurring revenue.

To be fair, I didn't clarify a timeline. I'm just curious what HNers think would be the fastest option. Fastest could mean 2 years.