How coordinated buying by retail investors has turned the table on Wall Street. Are there signs of a market bubble?

Topic covered include:

What are meme stocks
Why GameStop's stock (GME) has soared to over $300 from $17 in less than a month
What are short squeezes and gamma squeezes and how they can push up a stock price
How short-sellers including hedge funds are losing big against individual investors on the wallstreetbets subreddit
Is coordinated buying of options and stocks by individual investors illegal?
How market flows into stocks are taking precedence over fundamental data
Is the stock market in a bubble and how does the current market environment compare to the 1999 Internet bubble and the 2006 housing bubble?