Nobody is making you buy it. If there is a 10% chance that you are utterly wrong, then you'll get a game you enjoy. If you are right, then that will show up in the reviews and feedback, allowing you to avoid wasting your money. You have little to lose by encouraging the development of more games like the BG series, regardless of the name. If you want to criticize a release, it is more productive to do so once it is out and you can rationally assess it.
You make a fair point. My objection isn't really based upon wasting money though. I do indeed have little to lose by encouraging the devlopment of games *like* the BG series. I simply see no reason to attempt to continue the series itself. It was wrapped up quite well, and very successful at what it did. I'd have no issues with them using that setting. But once you title it Baldurs Gate 3 then for win or lose you have tied its fate to the old series. Sometimes things should end on an up note instead of continuing until they become terrible.
If the only thing that will stop you is when you finally make a product so bad that people wont buy it, then you cheapen the entire experience. Look at the last Indiana Jones movie. An extreme example, to be sure... but how much better a product could they have done had they attempted to create a new experience rather than just arbitrarily bringing up something old because they knew they could sell tickets? Or Star Wars? We went from the awesome original trilogy to.... Jar Jar Binks.
Again, it could be good. But then why not make a 4? And a 5? Should a bad product be the only thing that ever stops a series?