The name (i.e., "Baldur's Gate") is going to attract many customers; it isn't difficult to pull in the dosh when you're riding a cherished legacy.
They could have called the game "Auntie Ethel's Saggy Tits", it would make little difference. It's a high quality RPG with Larian behind it who are known to make consistently great games, so the name has very little to do with its success during Early Access as it's merely a continuation of a story and there to interest those familiar with the franchise, but it does nothing for those who aren't.
Great games with high quality aspects are what attract people, even those outside the franchise that know nothing about it. Like Witcher 3, Cyberpunk, God Of War 2018, Metro Exodus, Mass Effect 2 or Divinity Original Sin 2... and so on. If BG3 was a terrible game, no name in the world would make it a success.
