Yeah that hood you have is toast. a dent that big the metal is stretched way to much to zap some pins on it and slide hammer the dent out.
Just bring the hopfully not dented hood to someone and have them respray it. $200-$400, lunch money for a body shop.
PS a shit ton of bondo (just slapping in a dent that big lol) is going to come off after a while. Like you said expansion and contraction (metal does it faster than body filler) will loosen it up over time. BUT not to say filler can never be used on a hood is not correct.