By and large, people are interested in VPNs because they're vulnerable, in some way or another. By becoming a VPN provider, you become a "pinch point" for the connections of a number of vulnerable people.

That way, a hypothetical bad actor only needs to compromise one entity (you) in order to gain access those people who rely on you.

Aggregating vulnerability makes you a target, and puts your customers at risk - Especially when you're relying on third-party virtualisation providers for your infrastructure.