There are plenty of good ideas in pure tech. I believe they are mostly in the small niche communities that are online that just aren’t well known - build something that a small die hard group will pay for. I’m more a fan of subscription money / fee-for-service than ad money which is inconsistent and requires lots of eyeballs.

I own a handful of profitable small online businesses and I’m building another in my spare time. You can tell by my user name where a lot of opportunity for small time programmers are (crypto in general really) but HN is ideologically opposed to that industry despite the profit opportunities being massive.

And finally I don’t want to reveal any here because I believe Peter Thiel when he writes that “every business has a secret”. On the surface level they are selling XYZ but the reason they win in a competitive market is only known to those running it.