Impermanent loss is the difference between what you get when liquidating your pool stake vs what you would have had if you'd just kept the two assets outside the pool.
This is also problematic because this is not a thing that actually happens in the real world. No one just sits on half of their stake being a stable coin: they trade it, and on average traders lose by a big margin.
Again impermanent loss only happens because you have LP tokens in the pool, which means your coins are for sale. Say the value of CUB goes from $5 to $10. The CUB that you personally have in the pool is going to be sold at $5, $6, $7, $8, $9, $10, and every value in between on the way.
So basically what you are saying is this: Well if you had just held the CUB and waited for it to spike to $10 you would have saved money! YEAH! NO SHIT! The entire concept of impermanent loss is flawed to the core and makes ridiculous assumptions like average people could have traded the market better than just farming the pools. Like, no... they can not... it is proven.
Again, arbitragers can not sap the LP pool.
I'm telling you this for a 100% fact.
No money flows from the LPs to the arbitragers.
Zero dollars.
Fact.
The only reason "impermanent loss" happens (terrible descriptor) is because your coins are for sale on an algorithmic curve and you are betting AGAINST the traders. LP holders are the house in the casino, and traders are the gamblers... so when people are like: "Well in this perfect scenario the gamblers beat the house on this occasion..." You can understand how that is an infuriating mindset that completely ignores the reality of the situation.
Again, arbitragers have nothing to do with any of this.
Impermanent loss happens with or without centralized exchange listings.
Outside exchanges affect impermanent loss 0%.