1
We risked to lose all our money.
We risked losing all our money.
Use risk + -ing, not risk + to-infinitive: ‘We couldn’t risk missing the train.’ ‘You risk losing everything.’
2
He put our lives in risk.
He put our lives at risk.
Use at risk, not in risk: ‘Their lives were at risk.’
Use at risk of + noun/-ing to say what the danger is: ‘The village is at risk of flooding.’ ‘People who smoke are at greater risk of heart disease.’