No, this is actually a myth. The state of South Dakota actually tries hard to replicate what they think you would have wanted to happen with your assets, even if you didn’t say what you wanted. If you die without a Will (known as dying “intestate”) your assets will pass in accordance with South Dakota law. The law starts by looking for people in your life that were closest to you. If you had a spouse your money will start there. In South Dakota, if you had no descendants or if all your descendants were also descendants of your spouse, then your assets will pass to your spouse. If you had descendants that were not from your spouse then your assets will start to be divided among different people in percentages.
Despite the state trying to replicate what you would want, it still is much easier to distribute your assets if you have a valid Will at the time of your death. Even if you end up distributing things exactly how they would otherwise be distributed under state law, dying with a Will helps expedite the entire process of probating your estate – it leaves no doubt as to where you want your assets to go to and also helps in naming the personal representative or executor put in charge of sorting it all out.