What difference does it make if your money is stolen from you slowly and steadily?
Why’s that an assumption?
It gives hashers plenty of time to switch from hostile pools
Why would hashers switch if they make more by not switching and taking the money instead?
To not kill the goose that lays the golden egg (expected value of perpetual income > a quick hit and run)
You are assuming that Drivechains will contain few coins to steal while also providing a large flow of income for miners.