I am shocked that IOTA has not lost more of its value.
It did not lost at all but gained. At start of the year price of IOTA was 15 cents now is 23 cents. This simply tells you that all prices in crypto have nothing to do with reality.
Later it counts only the difference of selling price and buying price. The price between the two event don't matter. You have at this time not any "gain", you have some IOTA's and maybe you will able to sell it later - OR NOT.