For these ones, I don't get when to use what. Could you give me a scenario for each or or explain to me on how to use each one?

1. It is less riskier than you would think. ( What would the second part of the conditional be? Why not just use #3?)
2. It is less riskier than you will think. (I never hear people use 'will' before, or very rarely, why? Why use #1 and not #2?)
3. It is less riskier than you think. (Fact?)

Jack, we just don't know what the other person thinks. Your three sentences suggest different probabilities in the speaker's mind re the listener's mind. Use them as you see fit.
Dear Jack112,

You must say: it is less risky.

1. «You» are not taking the risk.
2. «You» will take the risk, or will be present at the risk.
3. «You» already gave an opinion of the risk.

Kind regards, Emotion: smile
Students: Are you brave enough to let our tutors analyse your pronunciation?
 Mister Micawber's reply was promoted to an answer.
Dear MrM,

Quite so.

Kind regards,