Not sure about the funding, but it has been around for 20+ years. Maybe not tens of millions in VC funding, but it definitely has tens of millions of dollars worth of devs spending time on it.

Likely. Last year the foundation they're a part of received $25,000 in earmarked donations for Postgres which you can extrapolate over the 30 years it's been around to be a million-ish [1]. They've also received several million dollars in subsidies by starting as an academic project at Berkley in the 80s.

[1]http://www.spi-inc.org/corporate/annual-reports/

Likely through supporting organizations:

EnterpriseDB: $64.92M in 6 Rounds from 7 Investors https://www.crunchbase.com/organization/enterprisedb#/entity

Plus it is much more under development than 5-7 years.

If you assume an average 10 person years of development effort over the 20 year history of Postgres, absolutely.

20 years * LoadedLaborCost (USD$150k/personyr) * 10 people

=>USD$30m.

Yes, I think different companies invested that over the years. But perhaps more importantly it’s been 20+ years of development.

I'd assume the amount of work contributed to PostgreSQL by people while being paid by companies to do so is substantial.

I think you could relate that to funding?

Not sure that much, but Ingres was a sponsored research project and many people who now work on Postgres are employed by a consultancy.

It's received tens of millions of dollars of value in contributions, yes. Probably in large excess of that.