Though it may cost more, spreading functional knowledge across a greater base of people would be more resilient. Even if a company needs to pay an individual 10x salary consulting for a year, it would be in their long term best interest to spread a fraction of that knowledge across a larger employee base and document what is tangible. There is a limit (different for different people) across which an individual cannot cognitively support an operation. With years more growth every person would eventually reach their personal limit or lose interest. It helps to have teams of people that are smart enough to work through new problems and document procedures, playbooks, current states and retrospective reports and rely on institutional processes to maintain a coherent operation. Sometimes money isn’t the singular factor at work.