Board Game Arena

I'm trying out Arena-mode for the first time now, and just a few moves (~12% gameplay) into the game my opponent declared in the chat that:

"I will concede the game once we reach 50% progression. I rolled three times in a row only 2 or 3 which were the worst numbers for my position. No chance to come back from that.".

What happens at 50% gameplay that makes him wanting to wait until that instead of concedeing right away?
Less penalties?
Is is a frequent move Arena-players do; abandoning a game instead of losing it?

You just can't concede before 50% progression

Concede is not the same as abandon.

Concede can happen at 50% and means you surrender. It is used for 2-player games where the loss can be almost certain, and the player wants to save time.

Aah, ok! Thanks for clarifying that difference for me!