Solana is currently making a run at Ethereum. Bitcoin could be next.Bitcoin (BTC -2.41%) continues to reign as the world's top cryptocurrency, and it's not close. With a massive market cap of $1.3 trillion, Bitcoin is nearly four times larger than its next closest rival, Ethereum (ETH -0.49%). In fact, Bitcoin now accounts for a whopping 57% of the market cap of the entire crypto market.But a number of challengers are gaining on it, and the one that has the most upside potential over the next five years is ...