Veteran tech investor Jack Selby has warned there is still a mounting wall of worry about tech, and it would only take a few cracks to break the bubble.

Just a few months ago, he warned of the risk of the incineration of cash investments in the tech world. He doubled down on that as he joined me at the Bloomberg New Economy Forum in Singapore.

Mr Selby, managing partner at US-based venture capital firm AZ-VC, was in the country just a few months ago and issued a warning about the risks of investments in the tech and artificial intelligence space. He said it was only a matter of time before we tipped over.

It is now a question of what the catalyst will be to bring this irritation, as it were, to a conclusion. Nothing specific will tip us over the edge. There is not going to be one specific cataclysmic event that will cause it to implode, Mr Selby said.

He added that the warnings of a tech bubble have now become consensus.

"Imagine if there was another DeepSeek moment today, so another company that maybe comes out of China that no one previously had ever heard of, how much market cap do you think would get wiped out today? I would argue it would be much more than half a trillion dollars," Mr Selby said. "So maybe it's a trillion dollars, maybe it's a trillion and a half dollars. Whatever that number is, it's quite large."

The Nvidia results help steady the ship, giving everybody a little bit of breathing space and a moment to reflect on where they are. But Mr Selby is wary of the avalanche of deals from OpenAI and he questioned how much of them are actually legally binding or letters of intent.

He also said debt will be the nemesis. He has concerns of a mounting level of debt in these high-end tech and AI companies.

"I think there's even more fragility sitting here today because there's an awareness that we might be in this bubble," Mr Selby said. "And so there's a mounting wall of worry, it seems like, around this topic. It only takes a few cracks potentially to bring this to some sort of conclusion."