I think emergence of Bitcoin as a new asset class and its rapidly growing popularity has drawn significant attention of small and institutional investors, despite its inherent characteristic of volatility. Bitcoin's status is a new emerging technology has created sense of excitement among investors. It is widely believed that early investors in such technologies potentially yield huge returns on their investment. Stocks are a different asset class representing ownership in companies and stocks are influenced by various factors such as overall state of economy, company's individual performance and overall market condition. It is possible that some investors may allocate some portion of their investment portfolio in Bitcoin and other crypto currencies, while maintaining their interest in traditional stocks.
Crypto is very new while crypto is centuries old trading platform and much more stable and regulated. I don't think crypto has reached to a level that it has surpassed stock in terms of attracting capital from investors, stock trading is still first and foremost choice for traditional investors. Having said that crypto has its own success story in very short duration i.e. in just 10 years crypto has introduced itself to global audience. Its still a win for crypto if investors are sparing some part of there capital for crypto.