You must not be following the news. Many data centers get local power from on premises gas turbines and more than a couple are doing so illegally. Put ‘ data center gas turbine’ into your favorite news aggregator and there’s hundreds of articles about this.

Destroying the environment isn’t profitable.

Then they wouldn't be clearcutting the amazon rainforest.

Not being forced to follow environmental regulations (hence destroying the environment) is significantly more profitable than following them.

Or do you think op is talking about companies who produce literally nothing but harm to the environment?

Power plants typically connect via the grid, hence aren't local to the data center. Changing over is trivial.

But they don't have to, and they don't generally ask, just do.