My first post here, have been enjoying the videos.
 

Poker Stars $4.00+$0.40 No Limit Hold'em Tournament – t500/t1000 Blinds + t125 – 9 players – View hand 2444097

TournamentPokerEdge.com Hand History Converter

SB: BB = 17.7, t17694
BB: BB = 6.2, t6237
UTG: BB = 64.5, t64511
UTG+1: BB = 9.9, t9855
UTG+2: BB = 24.5, t24478
MP1: BB = 22.2, t22183
Hero (MP2): BB = 22.8, t22819
CO: BB = 9.0, t9049
BTN: BB = 19.0, t18975

Pre Flop: (t2625) Hero is MP2 with 6 A
4 folds, Hero raises to t2000, 1 fold, BTN calls t2000, 2 folds

Flop: (t6625) A 7 6 (2 players)
Hero bets t3000, BTN calls t3000

Turn: (t12625) 9 (2 players)
Hero bets t6000, BTN calls t6000

River: (t24625) 7 (2 players)
Hero checks, BTN bets t7000

I don't really have a good enough sample to say anything about villain but they don't seem crazy

So I only need to be right 18% of the time to call here but I'm not sure if I am. If I think about what he's calling the turn with, it's a lot of aces. Maybe an 8, but I doubt he has too many of those (88, 89s, K8s maybe? 78 got there). He could turn those into bluffs, but this is made less likely by the fact that this doesn't seem like a good place to bluff at all (is thinking like this exploitable?).

If he gets here with a larger pocket pair he's usually checking back. If he gets here with an A that I'm chopping with he's checking that back some too, but that's mostly just A8, flatting pre here with A5 or lower doesn't seem super common, even if suited. 

So I figure when he bets the river he has AT+ or better something like 90% of the time.

What's wrong with my line of thinking? Should I just call here incase he IS crazy? Am I missing something else?

Thanks!