the United States alone, ten billionaires had made "serious investments in private spaceflight activities" at six companies, including Stratolaunch Systems, Planetary Resources, Blue Origin, Virgin Galactic, SpaceX, and Bigelow Aerospace. The ten investors were Paul Allen, Larry Page, Eric Schmidt, Ram Shriram, Charles Simonyi, Ross Perot Jr., Jeff Bezos, Richard Branson, Elon Musk, and Robert Bigelow. At the start of the private space era it was not yet clear to what extent these entrepreneurs see "legitimate business opportunity, [for example], space tourism and other commercial activities in space, or [are] wealthy men seeking the exclusivity that space offers innovators and investors." There has been speculation as to whether these investments are a "gamble", and whether they will prove lucrative. As of the early 2020s some of these investments have paid off, with Musk's SpaceX coming to dominate the launch market in mass to orbit and with a $100 billion valuation. Other companies such as Bigelow Aerospace though have collapsed and left the market. Many startup space companies, such as Rocket Lab, have launched on the stock market for funding as Special-purpose acquisition company, but their SPAC values have been affected by market volatility. Venture capital investment Some investors see the traditional spaceflight industry as ripe for disruption, with "a 100-fold improvement a thousand-fold improvement ". Between 2005 and 2015, there was of private capital invested in the space sector, most of it in the United States. This liberalized private space sector investments beginning in the 1980s, with additional legislative reforms in the 1990s–2000s. From 2000 through the end of 2015, a total of of investment finance was invested in the space sector, with of that being venture capital. In 2015, venture capital firms invested in private spaceflight companies, more than they had in the previous 15 years combined. , the largest and most active investors in space were Lux Capital, Bessemer Venture Partners, Khosla Ventures, Founders Fund, RRE Ventures and Draper Fisher Jurvetson. Increasing interest by investors in economically driven spaceflight had begun to appear by 2016, and some space ventures had to turn away investor funding. CBInsights in August 2016 published that funding to space startups was "in a slump", although the number of space investment deals per quarter had gone from 2 or 3 in 2012 to 14 by 2015. In 2017, CB Insights ranked the most active space tech investors, ranked from highest to lowest, were Space