Is it me or Assassin's no longer furfill the criteria of "High Risk"?

UPDATE: A little mistake I made in the title (fulfill*).

There are certain Assassins who have self sustain (Rengar, Akali, Evelynn) that allow them to survive in pretty much any case.

I was also going to mention Pyke but I decided against it because he's a support and based on his kit and how he kind of can't solo lane, he needs that sustain to be able to help in team fights.

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Rengar: his W allows him to heal for 50% of the damage he took TWICE, and on top of that he is able to Cleanse himself of any effects he is under.

Akali: To be honest now she doesn't sustain as well as she was able to before the rework. But it doesn't excuse the fact that she can still sustain well if she does buy Hextech Gunblade and even Death's Dance (something that a few streamers have been trying out such as; Professor Akali and Box Box).

Evelynn: the thing about her healing is that it makes sense thematically. With her constantly lingering around the enemy, refusing to leave them. But it doesn't mean that she should have a such a strong sustain where (example: she is able to heal from 20 health all the way to 350 at level 6).

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Then there are other champions that sustain incredibly well with an item such as Hextech Gunblade like Katarina for example.

Weren't Assassins suppose to be designed by the fact that they trade everything else for incredible damage and mobility, such as (lower defensive stats, lower base health).

I was going to mention that they are able to escape too well due to having tools like untargetability dashes but I set that aside as that's kind of crusial to fulfill the criteria of "high reward".

##What do you people think?