ok, maybe so.

why is an "online grinder" choosing to re-steal with so many hands that don't have close to 50% equity vs. a 40% opening range from the button?

because nobody except ridic pass fish open 40% from the button?

Armor, u really think your opponent is betting 22+ on the river? How is this complicated with PS? Just put in your opponents range the hands you think he will bet all three streets with, if your equity is large enough against that range call, if not, fold. FWIW, IMO this river decision is not close, but you need to come up with range you think he can have, not just take my word for it.

Ok, now I assigned the river range this way, would you guys think it looks reasonable now? This calculation dictates an insta-no-brainer call.
Also, another question - what be the right approach to try making turn call decision from multi-street perspective, i.e. something along the line of "I am getting odds of 2:6.5 so what my equity needs to be under assumption that he keeps barelling his entire range on the river"?

Board: 8h Kc 3s 7c Ad
Dead:

equity win tie pots won pots tied
Hand 0: 25.974% 25.97% 00.00% 60 0.00 { 2d2s }
Hand 1: 74.026% 74.03% 00.00% 171 0.00 { TT+, 88-77, 33, A2s+, K9s+, Q9s+, J9s+, T9s, 87s, A7o+, K9o+, QTo+, JTo }

P.S. potential problem wih this range is that I assume he will keep barrelling with all his bluffs, which is not necessarily true.

Strange. I can't imagine not betting an 8 on the river in most 3 handed games against a lot of villains

For value?

Obv

Even if I include combos that have an 8 in them, our equity falls just a tiny notch. So it still seems to be a call on the river.

this is med stakes, why expect ppl to justify dumb posts?