Extreme Market Board Undercutting is a Problem. Who ultimately benefits from this?

[hiedra]

It's not full profit.

There's opportunity cost. The time spent farming/gathering something yourself could have been spent buying the mats from someone else and doing something more profitable.

This applies to retainer ventures as well.

However, there are people who don't value their time or might find farming/gathering themselves as fun, so they see mat cost as 0 gil.

I also want to add that the items they are selling use mats that come from the new tomes. So even if they're self sufficient it still takes a considerable amount of effort to craft those particular items that they then ended up severely undercutting.