I coppiced our 30 year old Christmas tree in early October knowing Christmas wouldn't be the usual arrangements this year. It's sprouting well and will provide lots of branches for decorations next year. Sprouts looking good, most likely because I am treating it carefully and remembering to water it. Gotta love Hoop Pines in pots!
We used to have a native (Rottnest island) pine in a pot but the caterpillars found it. I spotted one masquerading as a twig, and removed it, then another and another and by the end I had taken 100+ caterpillars off and destroyed them, but the tree didn't survive long after that.
Maybe you removed the support 'pillars.