Because they don't care. People get DUIs without money as well, and having the money doesn't mean they'll make a better choice. It could be a lapse in judgement, them being an asshole, or not having enough money; but odds are it's not about money.

Driving under the influence is one of the few things were I'd argue that 99% of the time, the person is an asshole. And if they are an asshole and don't care about others safety, then having money will only make that worse because now they've got nothing to fear from being caught. Most likely scenario in their mind is they have to pay a relatively small amount of money.

Besides, most people won't know or care. Even if they killed somebody in a crash, it will likely not be a big deal in the long run for them.