If I own 20% of a business worth $50m as a VC, and I run a $10m fund, then I will make 20% carry on the $10m exit. That's $2m in my personal pocket, pre-tax.
If I can facilitate a deal through a highly personal contact (i.e. close friend) where the company is sold to BigCo for $50m, and I can also charge 2% of the acquisition value to all investors (i.e. in line with what an investment bank or broker charges) then I pocket another $1m. So now I made $3m.
There is nothing inherently unethical about wearing two caps if you actually put a deal together -- whether that is raising capital (equity or debt) or facilitating something. Though in this case there MIGHT be a conflict of interest. But taking small percentage commissions is very common in business on certain transactions.
If an investor is already invested in my company, then the expectation is that they are already trying to help me fundraise from future investors and helping me to realize exit with potential acquirers. So I shouldn't have to pay extra.
Obviously there is likely more to this story, but on the average this feels perverted.
But if it's a sinking ship then the personal relationship might be worth more to the fund manager than trying to save it by making a small acquisition.
Honestly, like you said it all depends on the context and we're not hearing the full story.
I also wouldn't be surprised to see this more in Europe, where most of the VC funds invest government money (money from the EIB, local government funds, etc)