Trump wants to run the United States the way he runs business, selfishly and with no one else's loyalty or feelings in mind. That might make him money as a realator, but as a president, he will ruin the United States and start another World War, with almost every country against the US.
Yes, Trump's stance on defending NATO allies shows that his ideas are not well thought out, and he gravitates to the most convenient answer for the situation at hand. Trump is not a deep thinker, based on the words that come from his mouth. He is an opportunist who says what he thinks will get him ahead the quickest.
Donald Trump has flipflopped on everything from who he's actually insulted to more serious matters such as his political opinions and goals. In one such instance, Trump has been incredibly unclear about what he plans to do with our allies in NATO. I think this means he can't be trusted to actually serve confidently as President, and in fact could create more trouble for American citizens.
Yes, Trump's stance on NATO allies is further proof of his hypocrisy and inability to do the job. There are many instances that prove Trump will not be an efficient or even good president. His stance on defending NATO allies is one of them. Trump is definitely not up to the job.