Why PostgreSQL?

Ok, I actually know the answer to the question in the subject line, so I
don't need anyone to point it out to me. Instead I would like to see answers
from a different angle.

Since the .ORG Registry was moved to a PostgreSQL database, I know it makes
a strong argument for OSS in the commercial/government world. I know that
PostgreSQL is a solid RDBMS and that it can get the job done.

What I want to know is how can one persuade IT managers and decision makers
to go with PostgreSQL, when most probably haven't even heard of it? Most buy
either Oracle, Sybase, or MS SQL Server because that's all they know or
merely for the fact that money is not an issue. Companies may also choose to
go with the bigger name RDBMS because there is also a readily available
supply of DBAs that can support these systems. If a DBA was to leave a
company, then downtime would be minimal.

I received the New Riders PostgreSQL book today, but I'm now contemplating
whether or not I should master PostgreSQL. I decided to do a search on
Monster for PostgreSQL, and only 7 results came up for the US, with some
requiring experience in PostgreSQL OR MySQL. This has its advantages and
disadvantages. Advantage, job security, if I'm the only one who know
PostgreSQL, then it would be tough to get the boot. Disadvantage, the demand
isn't high, there aren't many job openings for PostgreSQL DBAs.

My second question is, "Why should I dedicate the time to gain expertise in
PostgreSQL?" My main reasons are 1) If I wanted leave my company, there
wouldn't really be a full-time PostgreSQL position open, 2) If I could
persuade my company to base their whole information architecture on
PostgreSQL, and then I left, it could very easily leave a bad taste in their
mouth after spending months trying to find a replacement.

I apologized for the lenght, but I hope my questions are clear.

Thanks,

Derrick Rapley