Popular stock trading app Robinhood was on the lips of every pundit, politician and punter this week, riding a promise to “democratize finance” — but its denizens are in revolt and its future is uncertain after it restricted trades of GameStop and other unlikely hot stocks.

The app is a victim of its own success — and missteps.

After its users helped goose the shares of GameStop, AMC Entertainment and some other retail stocks its online boosters claimed were undervalued to meteoric levels, Robinhood on Thursday restricted their ability to make trades. Users could sell but not buy more stock as it underwent high volatility.

Rumors swirled in the information vacuum, invoking establishment forces that were supposedly pressuring the app to tighten the screws. And then, late Thursday, Robinhood revealed it had raised $1 billion from its investors to shore up liquidity and cover the unprecedented volume of trading.

"We were not forced by anyone to restrict trades," Robinhood CEO Vlad Tenev told CNBC on Thursday evening. "We did this on our own, but there was no liquidity problem. We did this proactively."

Some employees said they feared the company was straying from its mission statement according to messages posted on Blind, an anonymous message posting service that verifies corporate email addresses before allowing posting, reviewed by tech website The Information.

“This sets a horrible precedent,” one message read. The "blowback" will be like that when the app crashed during a March rally, except “on steroids," the user wrote.

Enraged users filed a proposed class action suit. Regulators have taken notice. Congress is gearing up for hearings. The Securities and Exchange Commission, the country's top financial regulator, said on Friday it would “closely review actions” by companies that “may disadvantage investors or otherwise unduly inhibit their ability to trade certain securities.”

The new heat will add questions for investors, especially since the company is planning to launch an IPO this year.

“They were totally unprepared. It appears they had not committed sufficient capital to deal with the levels of volatility,” Joshua Mitts, a professor of corporate and securities law at Columbia Law School, told NBC News by phone. “It’s not normal,” he said. “No other brokerage as far as we know needed a billion-dollar bailout.”

On Friday morning, Robinhood initially eased restrictions on the volatile stocks, allowing more purchases, and their values began to rise. But as the day wore on and trading volumes increased, it restricted users to only buying a single share of the restricted stocks, and expanded the list from 13 to over 50.