"We continue to believe TSLA is fundamentally overvalued," noted the analyst, who's price forecast calls for a 65% plunge in the stock.

"Not to sound like an 'Ok, Boomer' to the younger investors rushing into TSLA share, but the recent price action brings to mind NASDAQ c. 1999," Barclays auto analyst Brian Johnson said in a note to clients titled "Party like it's 1999" on Wednesday.

Tesla's rip higher is garnering tons of attention from investors, especially younger ones. This has one analyst going back in history — about 20 years— to warn investors of any age about similar high-flying stocks that crashed back down to earth.

Demand is high for Elon Musk's electric-auto maker that has roared more than 100% in 2020, and nearly 40% in the past two days. More than 22,000 investors bought Tesla's stock for the first time on millennial-favored Silicon Valley stock trading app Robinhood in the past three days. Plus, when you type in "should I" on Google's search engine, the first auto-fill recommendation says "buy Tesla stock," further demonstrating interest.

Some investors say the mania around Tesla's stock is resembling past bubbles like the dot-com bubble in the early 2000s, internet stocks exploded and eventually collapsed, or bitcoin's unprecedented run to nearly $20,000 a piece in 2017, following its 65% crash the next month.

Johnson finds a particular resemblance between the unstoppable enthusiasm over Tesla and Qualcomm in 1999. Cellphone chips were indeed the future and investors considered chipmaker Qualcomm the pure play for the trend. But Qualcomm's stock got a bit ahead of the long-term opportunity.

Some investors see Tesla as the pure play for electric-car markers, fueling the stock's massive rally.

"And while even more cynical bears than us might compare TSLA to dotcoms that flamed out to zeros, even solid companies that were technology leaders around key building blocks of the internet and mobile telephony – e.g, QCOM, CSCO, ORCL – had parabolic price inflections in late 1999 that ultimately returned to earth by the end of 2000," said Johnson.

Barclays raised its price target on Tesla to $300 per share from $200 per share, which is still well below Tesla's $887.06 per share closing price Tuesday.

Ultimately, Barclays believes Tesla in overvalued. Nevertheless, the firm said its "recent price action opens up the possibility of raising capital cheaply, and hence reduces that chance of a stalled business."

Johnson has an underweight rating on the stock, which is 17% lower Wednesday.

— With reporting from CNBC's Michael Bloom.