It was a refundable deposit (and small), so I wonder how many people were even that serious - no real commitment.
2019 USA annual car/pickup sales were ~17M. I find it very hard to believe that 10% (2M cybertruck pre-orders) of those purchasers were seriously interested in a cybertruck - it really is not a design made for mainstream tastes.
If you owned a company and announced a product that 2 million people went and paid you $100 each for to preorder it, Im pretty sure you would think differently.