Investment costs money but why would investments hurt? What hurts is the loss of supply.

The money is spent on something and comes (hopefully) with a positive RoI and NPV. And you could borrow to build to reduce own capital outlay.

I don't think there was a lot of new energy production was put into place, though.

RoI isn't instant. If it takes you 20 years to build as much supply as you need then you're spending money over that time to try and get back to where you were.

And spending money on one thing means you don't have it for something else. Even if you're borrowing, you can borrow less for other things, unless you want to break your credit score, which would also hurt.