A mini fridge should last between 10 to 15 years on average.
However some mini fridges may last as long as 20 years but usually if you get 10 years out of a mini fridge today you're doing good.
The mini fridges and appliances made today are not made of good quality or long lasting materials and they are not made to last too long.
My friend has a 40 year old sears cold spot mini fridge and it's still going strong and he has it in his garage and he bought it at a yard sale.
But today you're lucky to get 10 years out of a mini fridge.
At least a new mini fridge is pretty cheap so even if I got only 5 years of use out of the mini fridge I'd be happy.