Everything you do in the game is a risk. If you choose to just play passively there's always the chance. Some plays are riskier than others. In terms of passiveness vs aggression, I usually play passively, but occasionally I play fairly aggressively, especially when I play someone like Leona or Naut.
Some games I play very risky and will risk tower dives Going all in in a team fight. Every move you make is a risk in this game.
The moment you leave your base you're taking a risk. Leash the buff for your jungler early game? You're risking dying to an invade or getting badly hurt and losing the first fight in your lane. Start a fight, and you risk the enemy managing to do more damage.
Everything has its own risks and rewards its about choosing which ones are worth it or even viable.
Xbox 360 GamerTag: HolyKnight22 PSN: CrimsonDivide
I would say about 4. Even as support I want to get my ADC fed as all hell, I tend to play aggressive supports like Taric and Thresh and am perfectly willing to die myself if it gets my ADC fed. At top or mid I tend to be equally reckless, my lanes are almost always high kill lanes, be it I get a ton of kills, equal kills and deaths or sometimes, lots of deaths, though if I die twice I'll be more conservative from there on out. Nothing to do with calculations or strategy, I'm just aggressive in game by nature.
I find this is very role dependent. As a jungler you are all about the risk management of anything you do, more so than the lanes because the things that a jungler can do to swing a game around all have innately more risk I find. The more warded and aware you can be, the less there is obviously.
As an ADC, on the other end of a spectrum, I'm all about not getting murdered and safely farming to be honest. At least until team fights start to break out.