Am I missing something extremely obvious here...

When I started looking at UuA flights I noticed that the cost of the 'paid for' class seemed always to be very high, with the Avios then added on top.

I've just done a like-for-like search on a couple of different flights (both intra-Eu and long haul), and found that the standard cost of a flight booked with money, is WAY below the cost of the same flight (at same class) pre-UuA.

e.g.

LHR - ARN, Outbound 19th September, Inbound 21st September, Club Europe:
£390

Exactly same flight, UuA from Economy to CE:
£580 + 15k Avios

How can this be worthwhile? You're both losing money AND avios to do the latter option. Obviously the disparity is that much more pronounced on a long haul as well.

Please tell me I'm just hungover and confused, and not just hungover.