turn donk bet puzzles me,(yet I am lucid, (maybe not)) Live 20/40

[signal]

First of all, thanks for all the replies.

Secondly, a few things to clear up.
1. There wasn t a flush draw on the flop and the x was low & inconsequential (no str draws)
2. I was 90% sure that a raise would fold out the rest of the field.& honestly I don't recall exact reads on the other players except they were bad and I sensed almost no threat from them.
3. In fact, they all folded after & the donker won the loot.

This fold really bothered me and based on the replies, I will consider the calling down option in the future.