I am sorry, I feel stupid and still dont get it all. When EGLD will 5x in a EGLD BUSD pair, the impermanent loss will be insanely high, like 25% right? That would mean the rewards from lp and lp token staking must be more higher than 25% correct?

Now you make me doubt of the idea it already formed into my head LOL . How did you get that 25% ? Think of the price of EGLD for instance , can fluctuate . Also depends for how long you are planning to hold the funds into liquidity pool , if you withdraw within a day or two etc. you are playing a short game , risking to lose from the price fluctuations . If you are planning to hold for months/ years , the IL will be basically scrapped because of the large amount of MEX already generated by you as a long term LP.