Think of it this way ... you will share in 50% of his winnings, and 100% of his losses.
You are also helping fund his laundry and toilet paper bills.

I would not invest in someone who's life plan was - drop out of a university to play poker professionally starting out with $5000 whether his name was Einstein or Forrest Gump. I wouldn't discourage him from giving it a go - but it doesn't sound like a solid 'investment'.

Now if you've got some money to blow, and this guy's a friend - then feel free - but consider it (privately) as a gift to your friend and if you get paid out of it - that's a bonus.