Max Verstappen is the Achilles heal to both of them. Both have damaged their cars trying to beat him into the 1st corner in resent races.
Fair play to the Golden boy, a 4th championship well deserved. He just needs to understand that 50% of his honours should also go to the car he has been driving.
While I think both Vettel and Hamilton are aware of the potential of Verstappen, Hamilton did at least have the capacity to let Max go by unchallenged in Malaysia in those early laps. The only damage on Hamilton's car in recent races came courtesy of Mr Vettel declining to avoid an accident after he'd already wrecked his front wing. As far as I can think, the only damage inflicted on Lewis' car during races all season has come after being hit by Vettel.
Verstappen is a long way from being complete, but could take Vettel's spot as youngest ever F1 champion if Red Bull deliver. I suspect if it happens he will make hard work of it, like most first titles. While he is still a bit wild at times, I can't think of any drivers that have actually lost their speed after taming the inevitable flaws from their early F1 careers as people like to suggest every time a top notch new driver starts to make a name for themselves. I still wish they had kept his abbreviated name as VES on the time screens though.