Take any service or product needed, from office space to hosting to headhunter. Have a middle-man provide that service, and provide a kick-back / incentive / referrer fee to the person choosing the service or product needed.

Again, it is illegal, possibly fraud possibly other, and certainly not unique to startups. Things like competitive bidding attempt to mitigate this risk, as do knowledgeable advisors to investors. And many other methods.

If somewhat foolish as one's personal reputation could be dashed in an instant, a VC/PE firm managing other people's money may not like having their own gullibility publicized in equal measure, leading to an under-the-carpet affair, or something else.