Analysts estimate that the market for "delaying human death" could be worth $610 billion by 2025. But that doesn't sit well with Christian Angermayer, who co-founded Cambrian BioPharma and Rejuveneron, and whose family office Apeiron Investment Group has a special interest in expanding longevity.

"This is a nonsensical, imaginary number that is almost entirely made up by the cosmetics and supplements industry," Angermayer said of the $610 billion estimate. In his view, the total addressable market of longevity-related plays is both smaller and potentially much larger than that.

"Right now," Angermayer told TechCrunch, "the industry for actually delaying human death is zero, because there are no products on the market being sold that have been shown to delay aging. Once the first ones are proven in a clinical trial, we expect that to go from zero to a trillion-dollar industry within a decade. It will be that fast."

He's not alone in believing that. Interest in the space seems to be growing rapidly in the VC community, so I spoke with five investors to get a better idea of where longevity tech is headed and just how big the market stands to become.

According to JME Ventures partner Samuel Gil, the opportunities in longevity are "endless." "The space is only getting started now and will infiltrate all aspects of our life in the next five to 10 years," he says.

He added, "There are multiple angles to solve problems for very heterogeneous groups with different requirements. Health span versus life span, longevity for pets versus humans, biotech versus wellness, seniors versus young people, dependency versus autonomy, prevention versus treatment, analytics, education, infrastructure."

That said, some startups in the space are still looking for more sources of capital. According to LongevityMarketCap newsletter author Nathan Cheng and his partner at Healthspan Capital, Sebastian Brunemeier, startups that work at the intersection of biotech and longevity could still use more capital. "The entire field of longevity is underfunded relative to other areas of biotech and private investment," the pair said. "We expect that it will be another five years or so before longevity biotech enters the general investor consciousness."