That room full of insightful, creative people gets their money from venture capitalists/angel investors. The only role the stock market has is making it easier for venture capitalists to exit from successful investments. Without the stock market, there could still be investment made in early stage companies, but investors would have be more discerning about what they invest in because they'd have to make their money back through company stock buy backs, dividends or acquisitions.
The way that investment happens would most certainly change but, in some ways, it would change for the better. There would be far fewer photo-sharing apps and other such nonsense that really doesn't need to exist. And I'm still not convinced that tying our retirement savings accounts (401(k), IRA, etc) to the stock market is such a good thing. The stock market continues to go up and up, in part, because of the millions that flow into it each month from workers saving for retirement. This has a Ponzi-ish feel to it...in the same way that Social Security will run into problems when the baby boomers retire, the market will also start to decline as withdrawals from retirement accounts outpace contributions. The whole thing feels like a Social Security that Wall St gets to skim large amounts of money off of.
The stock market is A mechanism for investment. It's not the ONLY mechanism. We should be able to separate stock market criticisms from the ad absurdum argument against all investment.