Sorry to split hairs, but they're paying a reported €53m for Olise, which is around £43m. Similarly it's € for the sell on fee, so that's around £17m-ish paid over the next 3 years.
From what I've read on here from our resident Dutch and Bayern fans, he didn't exactly fail there but was obviously never going to displace the likes of Müller or Lewa. They obviously thought he could still come good otherwise they wouldn't have insisted on such a high sell on fee.
Sure he could fail hard, but that's true of any player. How many sure things haven't worked out? Look at Sancho! Signing ready made stars hasn't really worked out for us, so I don't really have a problem with signing players like this who appear to be on the up and might have something to prove.
He left Bayern to seek regular football after all, first taking a step down to Belgium and then one of Series A's lesser known sides, and found success at both.