Top 10 Cryptocurrencies by Market Capitalization. Source: CoinMarketCap
As for Ripple (XRP), it's been a race to the bottom, its market cap has collapsed from a high around $130 billion in January 2018 to the current one under $9 billion. At one point XRP was jockeying for the number two position with Ether (ETH), however, currently, the combined market cap of XRP and USDT is still $5 billion behind Ether.
USDT vs. XRP market capitalization. Source: Cointelegraph, CoinMarketCap
USDT trading volume dwarfs XRP’s
Perhaps part of the problem for XRP is a lack of traction with retail investors. In terms of daily trading volume, USDT dwarfs XRP. USDT’s average daily volume in May has outpaced XRP’s by a factor of 25.
USDT vs. XRP volume. Source: Cointelegraph, CoinMarketCap
But this doesn’t mean that the race for third place is over. With a decent bull run, XRP could blow past its stablecoin rival, which cannot move up or down by more than a few percentage points.