AFAIK, RBTC is not tradeable on the exchange nor officially listed there. Gate.io has some bug on adding token on there exchange even though its not tradeable there.
Yep, that's the big mistake that OP did as according to both CMC and Coingecko, RBTC is not tradable on Gate at all. That still doesn't explain why minimum withdrawal and withdrawal fees are so high. It doesn't make any sense to me, other than to entrap those who don't pay attention and don't check properly before depositing.
What exchange you are using to determine the rate of 1RBTC=1BTC?
Both Kucoin and Bitfinex have very similar RBTC/BTC ratio. On Kucoin its 0.99 and on Bitfonex 0.98, so almost 1:1