Is there any reason why the US would withdraw from the Paris Climate Agreement?

President Trump is set to make a decision this week on whether to stay in or pull out of the Paris Climate Agreement. Trump has called the agreement “a bad deal.” But as understood, the Paris agreement is a voluntary one. So if the agreement is voluntary–without incurring any penalty if the terms are not met–why is it a bad deal?

From Vox:

 [The Paris agreement] asks participants only to state what they are willing to do and to account for what they’ve done. It is, in a word, voluntary…

Here’s how the process works. Each participating country determines, on its own, the policies and emission reductions to which it is prepared to commit. It then submits a Nationally Determined Contribution, or NDC — a set of emission targets and a plan to achieve them…

Trump can weaken the US NDC, without penalty. He can roll back all of Obama’s carbon regulations, without penalty. He can simply fail to meet the targets of the NDC, without penalty…

That means all talk of Paris being a “bad deal” for the US, or hurting US trade, or affecting the US coal industry in any way, is nonsense. Paris does not and cannot do any of those things. The US voluntarily offered up an NDC and can voluntarily offer up a different or weaker NDC any time it wants.