Because protecting his fee-fees is American policy now.

For the record, our president-elect is completely unfit for office. Today he tweeted a demand that the eventual replacements for the current Air Force One, the president's two dedicated aircraft, be canceled.

x Boeing is building a brand new 747 Air Force One for future presidents, but costs are out of control, more than $4 billion. Cancel order! — Donald J. Trump (@realDonaldTrump) December 6, 2016

Several things are wrong with this. First, he's (once again) lying. Costs aren't $4 billion. The planes aren't even being built yet. What exists right now are contracts for $169 million to design the replacements, because the current planes reach the end of their expected 30 year lifespan next year. Even going according to schedule, the new planes won't be ready for five years after that.

But why did Donald Trump suddenly take to Twitter to denounce Boeing for an "out of control" "$4 billion" contract for a replacement Air Force One? TPM notes that it quite possibly could be a tantrum-fueled attempt to damage the company after Trump read earlier in the morning that someone at Boeing criticized him.

[A] Google search (which is obviously an imperfect measure) suggests that the Tribune story was the only published mention of the [Boeing] speech in the last 24 hours prior to Trump's tweet. It seems at least plausible that the Tribune story was the first or one of the first reports of the speech Trump or his team saw.

What appears to have happened is that earlier this morning, the Chicago Tribune published a story reporting that a Boeing executive had some skeptical things to say about Donald Trump. We already know that Trump obsessively scans the news for critical mentions of himself. (We also know that he reacts to news he sees with immediate tweeted policy proposals, as when he Twitter-mused about stripping citizenship from Americans who might burn a flag as an apparent response to a Fox & Friends segment on flag burning that had aired just beforehand. The man is a child.)

In any event, a mere twenty minutes or so after the Tribune story about a Boeing executive criticizing him was published, Trump suddenly found a strong opinion over one particular Boeing contract, declared it "out of control," and demanded it be canceled.

The result was a new out-of-nowhere presidential demand, and a sudden nosedive for Boeing’s stock.