Thank you for this great blog post!
I experienced the mentioned issues. Sometimes it also comes down to very small things that make you feel excluded like not drinking beer and being vegetarian.
I disagree with some other comments that this kind of culture arrives from being a start up (so founders hang around all the time with each other) and that this culture grows organically. Also in a start up a diverse friendly culture can be easily designed from the start. As a founder you have to be aware of this issues and then be a role model and simple work less hours. You don’t need to be busy all the time as a founder. It is even dangerous because you tend to have too many responsibilities and then later it will be really hard to delegate tasks. I would even go farer and say that an all-time-busy-founder creates fear and uncertainty. For me a good founder is well organised, calm and a team player.