I decided to try to learn adc as secondary role
Then I quit because these pieces of shit exist

<== still in the game
Then I quit because these pieces of shit exist

<== still in the game
I stopped because all my supports want to play lux
ADC is the worst role to climb as even without autofill, which just makes it 12313123 times worse because for some reason riot refuses to admit it shouldn't exist below diamond where its needed so you have a first time sup player every few games which is a garunteed loss.
I stopped playing because they changed
and 
is why i hate adc
Why not play Ezreal? Ezreal is an ADC and beats all of the champions you mentioned. One of the perks of being the best champion in the game and perfect in every single way.
Pick any of these depending on what you vs and there you go.
Most of the time the problem I see with ADCs is they pick things that literally do not work with their comp or against the enemy team like picking Ashe into a full dive assassin comp then saying ADC role sucks lol even when ADC was the #1 role even doing something like that was a retarded idea.
If you are first pick then pick something with mobility not just yolo pick an immobile ADC then complain when they pick something that destroys immobile champions.
As an ADC main, I believe the role is pretty much the hardest one to make a difference in the game. Unless you're playing Draven and stomp the lane as hard as they can't comeback, you're too attached to teammates decisions.
When you're playing a jungle carry, you can get kills, and walk around the map making sure the team does not comeback.
Just think about this a moment. When you see streamers doing Bronze to Challenger, what role do they play? Jungle? Mid? It's probably gonna be jungle. They're basically the only role where you can abuse your skill advantage over the enemies.
Depends on your support. Janna got a nice buff and she's a really good counter to assassins.
I tried to play a game
then quit because these
still exist
As an ADC main, I can confirm that it's a very volatile position due to the meta and where Riot decided to push the game.
The problem I see with a lot of ADC and Supports is that they often don't know how to work together. Like I'm playing
and my ADC literally flashes away from me after
ultis him/her making it harder for me to stun with my Q/E/R,
,
,
or whatever. When I'm playing ADC, my Supports are... As a Support main in older seasons, I'll be blunt: they're just bad.
It may not be you're bad at ADC or that assassins can get you. There are actually ways to beating assassins as a late game ADC, the trick is to just get there which is reliant on vision control for you to keep scaling and rotating safely which means its a Support thing. You only really need 2 wards at properly placed points to provide safe vision with a 3rd for a location thats sort of a just in case. Whether or not you should blame your Support is more like understanding whether or not you're doing what you believe you should be doing as a member of the team in the ADC role.