If you're talking about good managers, then yes, having more people creates more work.
The lazy middle managers aren't interested in hands-on middle management, though. They cultivate teams of people who can self-manage or be managed through fear. They take the people who need a lot of attention and they transfer them to other roles. They penalize anyone who asks too many questions or requires too much management input.
These aren't good, hands-on managers. They may be great at talking big in meetings and schmoozing around the office, but they're not putting in the work to be hands-on with their employees.
Sure, but the exceptions do all the hiring!
I agree, which is why people who do know that tend to be extremely hesitant to hire (they’re trying to preserve their own local quality of life). But as the sibling comment says, this realization only occurs to good managers and even then it takes some time.
I think hiring is all about making peoples lives easier (to the extent they’re allowed). However, there’s a cynical way to look at it and there’s a positive way to look at it as well.
We look at people and they generally work 8 hours a day, 5 days a week. Is it going to be surprising we need a whole lot of people running global operations 24/7?
Most importantly, there are very few managers and business leaders who think "You know what would make my life easier? Having a lot more people to manage!" The usual reason people are hired is because the needs (or anticipated needs, which can often be wildly off as we've seen recently) of the business require it, and without more people there will either be lost business opportunity or risk that existing employees are working at an unsustainable rate.
I'm definitely not saying that businesses can't be inefficient, but when I read your sentence "Everyone’s number one objective in any company is to make their individual life easier" (with a "full stop" no less as if that somehow guarantees its unassailability), I honestly didn't know what you were talking about.