Pardon my ignorance of poker, but won't the opponent notice that you have suddenly raised the stake and that something could be afoot?
So - you play for 4-5 hours, folding on weak hands, and always raising on strong hands, and then, once people think you are a grinder, you start betting on weak hands; other players fold because they were used to you betting high stakes only on strong hands, you take their money.
For example, you might always fold low pairs 22-66 initially (and perhaps conspicuously reveal that you folded them) but then start raising with them later. If your opponents were paying attention, then (a) they will think you have a good hand, and may be scared into folding right now, but (b) even if they don't, they won't suspect you of having a low pair, so that if e.g. a 2-6 comes up on the board and gives you three of a kind, you have an advantage because your opponents won't consider that you have this hand.
In my opinion, the parent example was rather oversimplified. If a player started playing more aggressively, that would be an obvious 'tell'. Most opponents would recognise that they should play more conservatively until they figure out what's going on.
However, this strategy really just needs one sucker: if it works, it works.