I think for me, I can't bring myself to spend £££ or even ££ on an advent calendar now, unless all the products are something new & exciting & something I will use.
But £40 on an M&S calendar?
Yes, I can probably do that, just to give myself a little treat every day in the run up to Christmas, and I will probably use most of the items, even if they aren't the most exciting.
Plus I can spend the qualifying spend on stuff like socks & pants for the DC and feel super-virtuous that I am spending money on them 