It's a mix of all the above, I've written several OSS projects over the past 10 or so years. Recollecting on it, I typically get little value back by releasing it as OSS and license(s) pretty much guarantees this will happen.
If it's not shared at all few can benefit at all. So the goal is to strike a balance.
If it's not shared at all few can benefit at all. So the goal is to strike a balance.