It seems like they’re saying that corporate giving doesn’t necessarily pay out the investors.

But not all corporate giving/lobbying is for reasons simply defined in cost/benefit financial terms.

Also, this line

Contrary to these findings, the study found that corporate political giving is positively associated with market performance for firms in highly regulated industries.

begs a lot of questions about the mechanism by which that association occurs. If we’re looking at corporate lobbying to erode regulations (which would temporarily boost share worth and/or dividends, et cetera), then that associate is a clear demonstration of the benefit of lobbying/electioneering.