Why is fizz so hard to kill?

So I've been looking at Fizz health and the health of other champions who go mid to compare them. But it appears that Fizz has far too much health. Fizz rests at 2020 hp at level 18 where as Leblanc only has 1791, I know that might not seems like a lot but 200 health can make or break a kill. (I've had too many games where he limps off with 20 or less hp) Now I could see Leblanc with more health than fizz as they have similar kits but Leblanc doesn't have a built in stasis/invulnerability. Yes I have taken into consideration that Leblanc has ranged autos, but Fizz clearly does more damage in numbers and in practice. I'm just confused as to why fizz has more health than almost every other mid laner when he is clearly one of the biggest threats to mid/bottom health.

Right now I'm just asking for fizz to have his health set to that of similar mages/assassins in the mid lane. Because right now he has way too much health for the damage he can spew out. (I compare Fizz to Leblanc due to their similar play styles and similar kits.)

EDIT: possibly keep his Base hp the same but reduce his scaling.