Their previous game Divinity Original Sin II was..
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With the success of their previous games they had no need for a kickstarter campaign for BG3, because they already built up a war chest that could carry them through to early access release. They knew enough people where standing there ready to throw their money at them, because of their earlier work.
Also, many games have done kickstarter to get off the ground and then went early access afterwards. It's not about "double dipping", it's about get the project off the ground. And unless you show me the recites I doubt you spent a dime so far on this game.
Games that enter early access on steam didn't so without any funding before reaching that point. People doesn't work for free. Some do kickstarters, other might take up loans, whatever to realize their project at such a stage it can enter early access and get a cash injection that help towards complete the project.