Dont ever calculate your profit gains in USD or other fiat currency,because they dont increase in value the main aim of an investor or a trader is to have much satoshis because BTC is measured in sats,as the BTC grows sats value will grow too not like in fiat.
I think that you are wrong. You must calculate profits in fiat because that is what you invested in the first place and that is what you will take into youre wallet to pay for food. You must have a stable point of compare to see the proffit and thats why the best way to do so is fiat. You cant make a accurate calculation based on btc, another coin with high volatility.
And now about the OP topic. I think it is risky time to buy into XRP because it`s allready pumped hard and i think that there will be a correction soon.