It depends on how much profit you are making. As long as you can still be profitable on the old hardware you don't have to upgrade.

That's the thing though: a competitor with better power efficiency can undercut you and take your customers

	▲	tzs 8 hours ago \| parent [-]
		Or they could charge the same as you and make more money per customer. If they already have as many customers as they can handle doing that may be better than buying hardware to support a larger number of customers.