But the goal of taxation isn't to maximize the country's economic success or overall wealth.

It's to fund necessary government services (schools, courts, police, military, etc.) and to redistribute wealth (Social Security, Medicare, Medicaid, etc.).

We only want to maximize national wealth after we've funded government services fully and redistributed wealth (and sufficiently protect the environment, protect workers, etc.).

So if funding the IRS gets you back more money, that's always good, because it's by definition going to the things that we have democratically decided are a higher priority than maximizing national wealth. And if we democratically decide that we're spending too much on services or redistributing too much, then we cut those intentionally -- not "accidentally" by underfunding the IRS.

Even if under-collecting taxes is good economic policy by the extremely narrow measure of GDP, it's terrible national policy. It's like saying that accidentally redirecting an extra $500 per person to the military is good military policy. I mean, sure it might be. But that doesn't mean it's good national policy.