Remember that YC prefers to fund "naughty" founders, to use their own term.
What We Look for in Founders
4. Naughtiness
Though the most successful founders are usually good people, they tend to have a piratical gleam in their eye. They're not Goody Two-Shoes type good. Morally, they care about getting the big questions right, but not about observing proprieties. That's why I'd use the word naughty rather than evil. They delight in breaking rules, but not rules that matter. This quality may be redundant though; it may be implied by imagination.
I mean, if I had a friend who openly claimed to be 'naughty' in this way, I'd start being very cautious around them.
By not following those assumptions (rules) you can make a new better model which might have better accuracy at representative real world problem than the existing model.
It doesn't mean that it's unethical or morally wrong. It doesn't have to be.
I find it weird to say good founders should 'delight in breaking rules', as that is a really consumer tech biased (and frankly, privileged teenage male) point of view, where external stakes are relatively low.
That attitude can be pretty counterproductive in a lot of important industries. It may be necessary to break certain rules to achieve a larger common good, but to bias toward breaking them (rather than to see it as simply sometimes necessary) represents one of tech's worse qualities, and probably does a lot to filter out a lot of potential founders.
Also take issue with the idea that successful founders are 'usually good people'. At least in my experience most are in the chaotic neutral camp where they generally don't care much about externalities as long as they're not too bad or seriously affect them, and their ideas about 'changing the world' are generally indistinguishable from their own personal success.