I was trying to say that due to sheer number of potential planets around billions of stars in our Galaxy, 'water planets' are probably rare, but not
My hunch is that there are probably plenty (10,000?). If we have more than 10,000 planet bound sentients who can communicate actively (I.e. can
generate several Gigawatts of excess power), I'd be surprised.
I tend to look upon the Galaxy like a typical PC 'Roleplaying game' of 'Space Adventure'.
In it, you start with a few dollars, and you go pick a crew and equip a ship which will barely get you into orbit (of course you have no fuel!).
Then you mine until you have enough money to 'buy' attributes so your 'crew members' aren't morons; you buy fuel and then start to transport
parts for a Space Station.
From there, with lots more mining and finding clues and bonuses, you manage to get to the Moon.
It takes a LOT more money to get out of the Solar System, and a Star Drive is crazy expensive.
Only the most determined and clever game players make it even this far.
Indeed, if you pick the wrong crew, you might not have the 'Right Stuff' to get very far - you end up starting over a lot.
So to recap, yes it's key that water (or some kind of fluid/solvent) be abundant, I think. Any planets or beings that don't use it much would
probably be 'extremeophiles' and outliers.
Yes, I think that this, and several other things need to be 'added' to the Drake Equation. (perhaps the need for a large moon?)
Good topic, btw.