A "boss" is one discrete individual who can show up, and say "do this" or "do that" and you have, effectively, no choice in the matter at all. You're under that person's thumb and if they micromanage you, you're fucked unless you quit.
With investors, there is less likely to be one person who has that kind of power, and depending on how much equity you've maintained, or how you've structured your board, there might not be anybody with that power. Having to be accountable to a group, in aggregate, is a different beast... and the point is, you're accountable for the outcome but you have a lot more say-so in the "how" and "what".
But then, it's a dificult calculation. The more capital you apply at the company, the more money you must take out of it.