Thanks to all of you for your thoughts. I understand that I leave a lot of value on the table here by folding, and that I should in general focus on how to get stacks in here. What really confused me was the betsize, because usually he bets like 50 - 67 % pot. But downunder nailed it IMO: Why would he bet so much with the nuts. Some hand like an underpair or 99, or 8x type hands are much more likely (hopefully he does not limp/call with TT pre but I cannot exclude it entirely). Betting to end the hand.
I must admit I folded this time but I won a few smaller pots from this guy before and afterwards.
Oh and moving down in stakes is out of the question. While most of the guys are more in the 25k/year league, they would strictly refuse to play for smaller stakes. They also insist on allowing multiple straddles (UTG for .40, UTG+1 for .80, UTG +2 for 1.60 ...)
So all in all I am pretty happy with the playerpool.
Edit: Typo