When there is a fork, all the nodes in each branch of the fork is keen to know whether they are in the longest branch. Since the bad guy has control over the computational power, he/she can generate more blocks and possibly would own the longest blockchain. Now what would happen, the good guys attempt to switch to the bad guy’s longest blockchain?
Nodes accept the longest
valid chain. Blocks with an invalid subsidy will be rejected. Nodes will not switch to such a branch, regardless of its length.
The financial consequences of orchestrating such an attack outweigh any potential gains that could be made.
That is not necessarily the case. There have been several 51% attacks against certain altcoins that resulted in financial gains by the attackers.