I have been using PoolTogether for some time already (look at my ETH address if you are interested) but I have to the conclusion that there is no way to verify individuals. 
Now that’s not a problem at this time but maybe in the future when some changes are made to make a more fair system or just to verify people 
It could also be used to award people extra privileges.
For example entering a jackpot lottery with 1 ticket win chance for verified addresses only
But now you have been thinking why BrightID well I have been part of the BrightID community as a BrightID Star, and it is also linked to various other blockchain projects and creates a way to prove that someone is unique.
It could also generate new users via other projects. (more members yay 
)
Look at their website
It’s an excellent place to start proving that people are unique and have people only enter with one address. or verification
I also have addressed this as an other post with one of the solutions where it can be used for.
This is what I have in mind. I would love to hear from people what they think of it.
Yours sincerely,
Richard Jansma
Empowering the vision and possibilities of everyone and anything
RichardJansma.nl & RichardJ.nl
ETH: 0xa9196E531aE237B3edFE0B10299932CfD5dd494B
Opensea: RichardJansma