there's a huge leap from committing isolated crimes when it's the only way to defeat a Big Bad to adopting a life of crime to finance your operation.

There's also a huge leap from being the only Slayer in the world to commanding a global army of hundreds of them.

And we've seen that the lives and welfare of her Slayers are Buffy's absolute top priority. They're her personal responsibility, after all. Maybe she does feel some residual guilt over turning them all into Slayers without asking them first. ;-)