I mean if I buy just enough WXT for let's say 1% back and the worth of WXT drops, will I lose my rewards and have to buy more of them or it's forever

?
No, what matter is the amount of WXT you hold, if it is above 50k,100k or 250k and not their overall value.
https://wirexapp.com/wirex-tokenbut if it goes to zero....even wirex card owners who don't have a single token, like me for example, should leave less and less money in their balance.
