Coinbase (COIN) had a strong Wall Street debut, closing at $328 per share and valuing the company at $83 billion. Analyst Lisa Ellis of MoffettNathanson believes the COIN stock still has a lot of upside potential, with a price target of $600. It's a "must-own" for any long-term growth investor, according to her. After a major inrush this year, Ellis predicts a 35 percent drop in crypto transactions in 2022.