Because our current batch of politicians(with a heavy emphasis on republican politicians) are so utterly hypocritical and have no shame. So there was a huge niche available for someone to actually make a living making fun of their character flaws and hypocrisy!
Here are some examples:
1. Here are the republicans complianing that the Buffett rule will ONLY bring in $47 Billion but we need to defund planned parenthood because it costs us a whomping $363 million.
2. These videos highlight the republicans complaints about Mitt Romney, followed by their enduring love for him once he won the nomination.