This was helped by two of my cofounders having a spouse, and one cofounder having children. Priorities and behavior are different for a single person than someone in a relationship.
Being in a relationship or having kids is not the only route to having that sensibility in life. I was single even when my cofounders were not, yet I had a pretty sensible life, in spite of dating and trying to find a partner for life while also starting to build a company. I think the influence of my other cofounders, who had dreams and aspirations outside of just the company, was a strong tempering force to me or anyone else in the company getting an unhealthy tunnel vision.