Postgres is an anti-Oracle conspiracy! Just like Linux is actually a copy of SCO Unix. Or was it MINIX?
Regardless, Linux is an anti-Microsoft conspiracy! There's no "community" behind Linux, just a megacorp. All those kernel mailing lists are just a fabrication!
Yes people get paid to work on open source, and it's in the employers' interests. Not necessarily with the purpose of undermining competitiors, like your paranoid delusions would have us believe. Hardware manufacturers contribute to Linux because they want market share. Many projects start as university research, eg. the BSD operating system. Very often internal projects that are not central to a business get open sourced, to get "free" help from others and to get geek cred. Others contribute to projects they have gained from, eg. Twitter and Facebook & MySQL.
You're not totally wrong - OpenOffice was allegedly open sourced "maliciously" but to dismiss all open source as a smokescreen is just idiotic.
So please pray tell which specific MySQL alternatives you refer to, and which specific competitors are behind them. And show the evidence, or shut the fuck up.