Well, I say it depends on other things you probably can’t know - like would you have been able to sleep like that for so long, upright, in your original Y seat? And in good shape (ie, no back pain, neck pain, etc.)?

if yes to both, then yeah, kind of seems like waste. If not, than, not at all. I kind of suspect the latter (and if not, then seems a waste to ever upgrade, unless you have some sort of affection for the food in C over Y).

i flew in C (pre-Polaris) on BOM-EWR once and slept about half the flight (~7 hours) in a row, though in lie-flat. I was impressed on being able to get that much sleep in a row on a plane. Not anything I’ve ever come close to in economy - and nothing I ever expect to do in Y. So I’d say you won.