Maybe:
Reputation
Now you give me some of it
All actions you do
Can make you get me, or not
If you're bad, I run
you get reputation for everything you do either bad or good rep
The more you get me
The less you need me for things
To selfish, I'm all
the more reputation you have, the lesser you will need to do stuff and some selfish people care about reputation only
Up and down, I go
From one host to another
Positive? Perhaps...
as people vote answers or questions reputation goes from one host to other
You have me, pockets!
Not real, not fake, not in.
You has some to give
i didn't get this part fully but last line says "You" (the owner of riddle) has some reputation to give