Even if it took a week it would be extraordinarily profitable over a boost.
In fact the botting to 60 phase would need to take 1.5 to 3 months for the boost to break even (depending on the boost price).
So for the TBC boost, we are looking at 2.5 months of nothing but leveling to be equivalent. So basically your bot probably takes 10 minutes a day trying to level, even the bots have 5 kids and 2 jobs to juggle apparently according to your logic.