甲斐がない/甲斐(も)なく => it's not worth one's efforts to do something N2
も同然 => just like; same as ~ N2
全然~ない => (not) at all N4
甲斐がある => It’s worth one’s efforts to do something N2
いぜん (依然) => still, as yet, as it has been N3
Invariant
~もどうぜんだ(~も同然だ)      => just like; same as ~ N1
当然だ/当たり前だ => natural; as a matter of course N2
も[同然「どうぜん」]だ => The same as saying A, as good as A N2
Adjectival, Descriptions