Not long at all, that's missing the point.
The point is that someone will want to fix something about their car, get stopped by these screws that they don't own a screwdriver for, and will have to make a decision: wait a week for the screwdriver from aliexpress, with no guarantee they will actually get their car fixed once it arrives, or... just take the car to the authorized service and get it fixed now. And they have the thing on Saturday and their car needs to work, and...
Some will buy the screwdriver, but that doesn't matter. What matters is that many people won't, and that's extra profit for BMW.