It probably depends on a few things:
- what price the car is.
- your annual mileage.
- how long you have a mind to keep it.
- whether you are prepared to over-maintain it and spend a bit more than for an equivalent lower mileage car.
- whether you have a buffer fund for any unexpected significant repairs/renewals.
A youngish car with a high mileage is a reasonable risk to take if its priced accordingly (in the UK I'd expect a residual value of about 20-25% for a BMW with that mileage, depends a little bit on model, etc, here they might expect more). That means that the future depreciation will me more reasonable because its already shed most of its value, but the off-set will be that spending on repairs, maintenance and renewals will be higher as more of the mechanical major items will be advancing towards the end of their expected lifespan.
If you do a small-ish mileage then the high starting mileage and the higher running cost (if you think of it as €0.0x cent per mile) probably won't be a big deal and the car will probably last you years. If you do more substantial mileage and intend to keep it a while then have a think about what kind of mileage it will have by the time you are done. Then think about the sort of things that you would be cautious of in buying a car with that mileage.
The likelihood is that you'll have some fairly significant spends to do along the way on major components. Some like dampers, clutches, etc. might well have already been done but are also likely to be well on the way to the next replacement. If you get through the ownership period without a big spend then consider it a Brucey Bonus.
The last thing to consider is whether you are bothered about the car having any residual value when you are done with it. If you aren't then make sure you work out a cost per mile based on zero residual value and see how you feel about that number.
For a car of that age with a more modest mileage I'd usually budget about €0.07 per mile for standard servicing, consumables such as tyres, etc. For a higher mileage car like you are considering I'd budget for an additional €0.05 per mile (the compensating saving is that depreciation on the higher mileage car will be a little more gentle than the more modest mileage one simply because it doesn't have as far to fall).
The key in deciding if this is the way for you to go is to determine if the extra repairs and renewals costs if more or less than the difference is likely to be between the residual values of the cars at the end of the expected period of ownership.