Compression ratio of 12.5:1 in that engine? I'd say about 50k before you're going to start having problems with the internals if you drive it like it's stolen. Probably the valve seals first but possibly piston rings.
The Audi R8 V10 can be used as a daily driver. The maintenance is not outrageously expensive nor is it cheap, but manageable if you have the money. If you have large amount of money saved up with a good income, you will be fine. Make sure you have the "Audi Care" warranty to avoid unnecessary expenses (except tires).
supercar engines last as long as regular engines, the main difference between them and regular cars is that their maintenance is a lot more rigorous and expensive. many owners don't use them everyday despite their ability because they most times have better everyday cars with softer more comfortable suspensions that wont rattle them around as much. Jay Leno even has a Lamborghini Countach (Lamborghini is not known for reliability especially before audi bought them) and has over 70,000 miles (112,000 kms) which is very high for a supercar especially an old v12 lamborghini. with an audi r8 you can expect it to last an extremely long time because they already know how to deal with that engine. (it was based on the 5.2L v10 from the gallardo which in turn was based on the engine used in the S6 and S8 cars which are meant to be actual everyday cars.
The Audi R8 V10 can be used as a daily driver. The maintenance is not outrageously expensive nor is it cheap, but manageable if you have the money. If you have large amount of money saved up with a good income, you will be fine. Make sure you have the "Audi Care" warranty to avoid unnecessary expenses (except tires).