Find some old warehouse, and hire an electrician to put some more wires in it.
Then hang up a sign in front that says "Data Center".
Then all you need to do is sign them up as they stand in line out front eager to get in to the "Data Center"
It's like laying golden eggs at night while you're sleeping.
If it were only so easy! Tough part is that these bldgs cost +$800 per sq ft to build, so financing not readily available without a huge amount of equity. And you need to have fiber connectivity from a number of carriers and ISP's to be viable. And you need to have the operational team to convince the user / tenant that it's a safe place for their data. Not cheap to put in place.