Even more than buying a new Prius or jetting off to Cabo for the weekend, the new money set here wants to keep investing — and believing. Backing another start-up is a status symbol, the No. 1 splurge, and it captures both the tech industry’s belief in the future and its fear of missing the next big thing.

“These are nouveau tech millionaires,” says Adeo Ressi, a coach for entrepreneurs. “It’s not that they don’t see the warning signs. It’s like roulette.”

Even before the fragility of the stock market became apparent, people here had been asking this question: Are we in a new tech bubble?

The optimists — or, some would say, the self-interested who stand to profit from the hype — note that the amounts being invested are nowhere near what they were in 2000, and that the companies this time are generally profitable and mature. The pessimists say yes, a bubble has been inflating, yet even they aren’t fleeing. They just hope to be the smart ones who get lucky and get out before it pops.

A bubble looks just like a boom, says Marc Andreessen, who touched off the first boom when his company, Netscape, went public in 1995. Frank Quattrone, the investment banker who took Netscape and dozens more companies public back then, says that today feels less like the height of the bubble and more like 1995, when tech companies were starting to go public but investors weren’t yet speculative.

Just four short years ago, social media and the iPhone were the hot new things, and money was sloshing around. But when the recession hit in 2008, Silicon Valley froze. Of course, that didn’t last long: by 2010, start-up investing was booming again with money from angel investors playing with their own cash, and this year the I.P.O. markets opened wide to tech companies for the first time since 2007.

Twenty-two tech companies went public in the second quarter alone this year worth $5.5 billion, the highest dollar amount since 2000, according to the National Venture Capital Association. Only six went public in all of 2008.