Over the past five years, there's been "an unprecedented amount of capital" poured into technology start-ups, he said.
There's no capital intensity for many of these tech start-ups, though, being as they don't need to build physical factories or stores, Gurley said. In turn, the only way to spend all that excess cash is to increase the burn rate, he said.
"The problem is, this growth at all costs mentality causes almost a substantiation of survival. It's much easier to execute unprofitably than profitably," Gurley said.
Read MoreAnother VC warns of lofty valuations, high risk
For example, one company could be profitable while another could lose $30 million annually, he noted.
"It's much easier to do that latter, so I think we end up with more companies at higher revenue rates where their business models may still be at question and that's what leads to the risk that I was talking about," he said.
If this "sloppy behavior" is not addressed by the tech start-ups themselves, Gurley worries it could eventually trigger a selloff.
Since Gurley first started sounding the alarm on this issue via Twitter last month, though, he said many company's board have started talking about this issue.