Selling decorations definitely does not make sense late in the game (when you are at the point where you can reset quickly, and can farm for more shares and buy all decorations). It maybe might be useful in early game - if you get the wrong decorations and cannot afford the right one. But I am not sure about that either.

Megacoin becomes a nuisance at higher levels - for manual clicking and especially for auto-clickers/mouse macros for shares farming. So much so, that spent 25 rubies to reset my skill tree, and bought everything again except for the Megacoin.