People who happen to be living in sanctioned countries can't take advantage of the traditional financial system, they can't make purchases on the Internet with their Visa or Mastercard, and they sometimes don't even have a bank account to make a deposit. Without globally accepted and properly working digital currency, they are cut off from the rest of the world and have to only transact locally like in primitive times when money didn't exist. Bitcoin solves this problem by giving these people the ability to join the party and transact with whomever they wish without having to ask permission. It exists to help people make trades with each other in a decentralized way regardless of imposed sanctions or other constraints; it unites people that otherwise would have been disparate.