Bitcoin (BTC -2.93%), the most popular digital currency, fell 18.6 percent in just 70 minutes on Wednesday. Although this is the case, the grandfather of cryptocurrencies seems to be just 30% off its all-time high, having increased 50% over the past 52 weeks. Bitcoin has a market cap of $907 billion. Only five corporations on the stock exchange have a larger market cap. You can find a lot of lower-cost alternatives to Bitcoin if you're interested in cryptocurrencies but concerned that Bitcoin is flying too close to the sun. Polkadot (DOT -8.93 percent) and Theta (THETA) are better options.The cryptocurrency industry is still young. With so much history yet to be written, predicting which digital currencies and tokens will survive is challenging. As a result, I prefer to stick with the evolving market's nuts-and-bolts infrastructure. On that note, Polkadot appears to be a significant long-term winner.