A good quality dishwasher should normally last between 5 to 10 years at least.
However I've had some cheaper dishwashers only last 1 to 2 years which was not very good.
I would expect longer than 1 to 2 years out of a dishwasher but most dishwashers you buy today are made so cheaply and with all the electronic stuff on them the dishwasher can go bad sooner than it normally should.
My parents had a dishwasher that lasted 20 years but today's dishwashers you're lucky to get 1 or 2 years out of them especially if they are the cheaper ones.
If you buy a higher quality brand dishwasher then it should last at least 5 years or hopefully 10 to 15 years..
If you get 10 years out of a dishwasher you're doing good and after 10 to 15 years you should be planning on replacing the dishwasher with a new one.
Repairing a dishwasher can cost just as much as buying a new dishwasher so I would not recommend repairing a dishwasher because something else can and will go wrong with it.