A common strategy for many startups is to reduce fixed cost expenses by sharing space with another business. Genuine VC states:

I am of the opinion that there is real value in the "hallway effect" of sharing ideas, experiences, and frustrations with others embarking on similar (but separate) endeavors.I am of the opinion that there is real value in the "hallway effect" of sharing ideas, experiences, and frustrations with others embarking on similar (but separate) endeavors. Via Sharing Space and More

Having someone to share the frustrations and experiences of starting a business grounds an entrepreneur because what they are experiencing is not unusual. It provides a sense of comradeship, belonging, and security.