Shares of Uber Technologies (UBER 0.33%) have been nosediving this month as investors worry about rising competition and the company's long-term growth prospects. As of this writing, the stock has declined 2% year to date and is down about 30% from its all-time high.Is this a great buying opportunity for investors, or are shares of Uber likely headed even lower?Investors are bearish on Uber stockUber stock's recent tumble began on Dec. 5 when Alphabet's Waymo announced it would be expanding to Miami. The se ...