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Look where the first gear starts and ends. Now look at the 7th.
Those are 2 different ratios, one will give you the high wheel forces that you need, the other will give you the top speed, but low force.
You can't have your cake an eat it. The only way one gear can span the whole wheel speed and have the same intial wheel forces, is if you engine can run with the road speed.
If you want to go 197mph with the high torque benefits of a first gear of 3.99:1 and final drive of 3.32, as your single gear, your engine has to rev to 40,000 rpm.
But since it can't you have to make do with the gears.