Playing while someone is watching me would not change my playing style, But saying that, if I ever accepted someone wanting to share the buy-in for a percentage of the winnings. that would make me more cautious, and change my game play, because I would be more worried of letting them down and losing their money.
I once was offered the chance of playing in a big tournament, by one of my friend's who asked to buy 50% of the action and I refused, not because I was greedy and wanted all the winnings to myself, but our friendship was more important to me, than the money, and I told him I just wouldn't feel right and it would affect my game play, because I would be afraid of making moves in the game and losing his money, as well as my own.
My 1st concern when buying into any
poker game is "Can I afford to throw this money away?" and if the answer is No! Then I don't play, it is as simple as that, Whenever I buy into a game, I never think I am going to win, because right from the start you are putting more pressure on yourself, I just want to play, and play the best I can, my only intention is beating the bubble and making the money.
Then and only then do I start thinking that I can make the Final table, and if I make the Final table it is only then that I start too think about how I can win the game. Setting your sights lower, means you have fewer disappointments, and you start to have more confidence in playing the game.
Winning is not always about being number one, and I have proved that to myself over and over again, you can come 2nd or 3rd, in every game and still make more money than a player who wins 1 in a 100 games, It is consistency that matter's when playing Poker and I have been number 1, Top of the League in our Pub Poker League, many times without even winning a single game, but I have made more Final tables than any other player.
Consistency!
When the fun Stops, STOP!