While I get wanting to preserve old stuff, we all know that entropy is inexorable, and that time gradually destroys everything. No matter how much care is taken, how controlled the temperature and humidity, what gloves people wear, etc, it's absolutely a given that everything present in any museum will eventually crumble into dust, get caked in hard to remove dirt, or break from accidents, careless manipulation, or things like theft and wars. Just look at what happened at museums in Ukraine.
At this point in time, with the amount of technology we have, scanning everything should be a no brainer. This gives tons of options. We can recreate objects when they get lost. We can make reproductions to show the same thing in several places at once. We can make a reproduction and let people touch it. We can make a fixed version to show people what the actual thing in its full glory looked like. We can make replacement parts when something breaks. I'd love to have 3D models available to the people.
And honestly, 12 million sounds cheap. The British Museum is huge. It has 8 million objects. The budget for the museum was £103.4m last year. It sounds like a very manageable amount of money and one that in my opinion is well worth it.