rw [← tsum_support_eq, Finite.tsum_eq_top_iff hfin] at h
case refine'_1
α : Type u_1
β : Type u_2
ι : Type u_3
s : Set α
n : ℕ∞
f g : α → ℕ∞
h : ∑' (a : α), f a = ⊤
hfin : (support f).Finite
⊢ ∃ a, f a = ⊤
case refine'_1
α : Type u_1
β : Type u_2
ι : Type u_3
s : Set α
n : ℕ∞
f g : α → ℕ∞
h : ∃ a ∈ support f, f a = ⊤
hfin : (support f).Finite
⊢ ∃ a, f a = ⊤