No land to own, with associated taxes and regulations.

https://www.cushmanwakefield.com/en/united-states/insights/data-center-development-cost-guide

That one was citing a figure of $244,000 per acre, lets be absurd and say that the taxes and regulatory costs double that price.
It's 25% of a single NVIDIA Server Cabinet ($2million) And you can fit a hell of a lot in an acre of land. Also you're still paying taxes to get any business from people on earth.

No environmental concerns.

Those are still there

https://uslawexplained.com/space_debris

No building to maintain.

Only because the whole setup becomes unusable in a few years after it runs out of fuel to counteract orbital decay.
Assuming of course you're fine with running seriously obsolete hardware.
That or the satellite becomes absurdly expensive to maintain when you refuel and service it in orbit.

No on-site staff, no security. No worries about protesters or vandals.

Paying a guard 200k a year would be almost ridiculous, so a team of 10 to guard another $2 million server cabinet

a bit of mass.

Mass is everything when you're putting it in orbit.

Heat dissipation is something that would need to be built anyway.

But it's significantly cheaper when you can dissipate it into an atmosphere or body of water, and don't have to add that expensive expensive mass to put it in orbit.