The fur trade began as far back as 1534 when Jaques cartier explored into Canada, meeting the First Nations and creating the first peaceful trade settlement. Not long after, a fashion trend began across Europe with beaver pelt hats. As the demand for the pelts grew and grew so did the number of trading posts in Canada. In the beginning, French and British traded with only things like pots and knives; things the First Nation's didn't have.
But as the First Nations and Europeans continued to trade, the First Nations began to run out of a need for the items the Europeans were trading. Therefore the Europeans needed a way to continue trading and find something the First Nations would be interested in trading for. Enter alcohol. The First Nations were immediately addicted and this opened the door for long term trading as alcohol is something that will run out quickly.
The British were the first to trade as there was so much competition in the fur trade at the time. The profits on alcohol were huge, it was very easy to make, transport and there was a huge demand for it after the First Nations were introduced. Meanwhile, the British were also diluting the kegs with water making it even cheaper to make and also to make it faster for the First Nations to run out.
Although some groups seen the effects of alcohol and banned it from their tribe, some weren't so smart and the tribes almost immediately got hooked on it. The First Nations believed that the alcohol brought them closer to the spirits (nicknaming alcohol spirits) and in First Nations' beliefs that was something important and highly valued. Another reason the First Nations liked it so much, the false sense of bravery which made various things easier.
Once the British and French saw how much the newly introduced alcohol crippled the First Nations' power they began to take advantage. The British and French began taking over the First Nations' land with very little backlash. Alcohol also hurt the British and French splitting them in two; those who support trading alcohol to the First Nations and those who didn't. This also caused the First Nations to threaten excommunication.
The negative effects of the alcohol trade can still be seen today as there is many First Nations reserves that are very poorly kept and flooded with alcohol. It is shown that on average that 33% of people 12 and old are heavy drinkers on First Nations reserves and 36% of First Nations, 12 and older off reserve are heavy drinkers. Although the stigma that all First Nations are alcoholics is not true there is a very high number of them that are.