Ask HN: technical co-founder looking for startup

I am 40+ year old CTO and co-founder of a firm that I sold a couple years ago. I'm ready to get back into a start up but I don't have any ideas ( I didn't really have an idea for the first company either ). I do have 20+ years of experience developing software as everything from dev to CTO. I also have significant capital to contribute as well as lots of time as I am currently retired. Spare me the lecture about finding an itch to scratch, even if I had that I still need to find a co-founder, CEO type to move forward. My company was in the ( puts on flame retardant gear ) HFT world but I'm not interested in working in that world. Most of my hands on development is low latency C/C++ work but in 20 years I've done some of everything. Any thoughts on how I should proceed?