How many people have $2 million in their 401k?

Could you please provide some insight into the question, "How many people have $2 million in their 401k?" I'm curious to understand the level of financial security among retirement investors and whether this figure represents a common milestone or an exceptional achievement. It would be fascinating to know if there's a growing trend towards larger 401k balances, or if achieving $2 million remains a goal that only a select few are able to attain. Additionally, I'm interested in understanding the factors that contribute to reaching this level of savings, such as income, investment strategies, and market performance.