When someone is in production mode, as in, working hard at a job, growing a business, shipping projects, etc., we realistically can’t be friends with them unless we physically work with them. It’s not personal, they simply don’t have time for anything but work and self-maintenance such as eating, sleeping, and exercising. Making new friends is not their priority. Often, maintaining old friendships isn’t even a priority. This is often the case for parents of young children, people in their 30s and 40s, and people launching a new business.
Conversely, if we’re the one in production mode and someone obviously wants to be our friend, it’s better to be honest and up front with them about our limited time and energy, and if and when that might change.