A well cared-for BMW will last a long time. However, any car with 200k miles will need considerable, ongoing service and repairs, since many mechanical parts will be nearing the end of their lifespan.
Unfortunately, BMW parts and service are more expensive than for the average car. It is not worth it if you have to look after these costs.
So, if there are service records showing lots of valuable work was done AND the price is low, the car may be worth a closer look. Otherwise, give it a pass.