Being a startup founder myself I share a lot of internal struggle you described. But what resonated with the most is your sentiment of how important upbringing and childhood environment is in providing one with resources to cope with the hard times and maintain mental hygiene. I am a Soviet child myself and from what I know some of the questions we ask ourselves would be framed differently or not occur at all for our colleagues, who grew up in western culture.
What I found for me is that being outside, even if it is just sitting on a bench on the street, helps to clear up the skies in the brain. Also, disconnecting from the world and connecting with the moment is important. Photography, as I’m sure you know, is a great tool for that.