Even in the depths of development, years after their last 'big' release, they're making profit (£3.5m last year, similar the year before), and have a strong net asset base.
So many bad assumptions in this thread about their financials and budget etc.
Their revenue would include contract/milestone payments from Sony (as well as royalties on sales), and there's no breakdown on which is which, but it's fairly clear from these figures that their budget is not huge (~£4m/year total costs) and those costs run well under whatever budget Sony payments+royalties are affording them.
If £4m/year is typical, and Dreams + Tearaway dev hasn't been much more than £20m total to date, and won't be much more before Dreams is released. I think it's quite reasonable for Sony to expect a return on that even if Dreams is only modestly successful.